Annif

550 Drop Python 3.6 support
541 Remove Maui and Vowpal Wabbit multi backends
551 Remove swagger-tester dependency
542/555 Add CITATION.cff file
553 Update Scrutinizer config
561 Set a 10 minute timeout for GitHub Actions CI jobs
565 Avoid coverage 6.3 as it causes some tests to hang

This release introduces a new spaCy analyzer and takes care of many maintenance tasks. The CLI usage is improved by shortening the startup time of some commands, the Docker images are now easier to customize, there are improvements to the eval command, and minor bugs are fixed.

The [spaCy analyzer](https://github.com/NatLibFi/Annif/wiki/Analyzers#spacy-analyzer) enables support for some new languages and can improve subject suggestion results. The spaCy analyzer and the language-specific models need to be [installed separately](https://github.com/NatLibFi/Annif/wiki/Optional-features-and-dependencies#spacy-analyzer). The Docker image distributed via quay.io includes the spaCy analyzer and the English language model, but no other languages.

The maintenance tasks include upgrading many dependencies, notably Omikuji to [v0.4](https://github.com/tomtung/omikuji/releases/tag/v0.4.0). The Omikuji upgrade brings faster training and predictions as well as reduced memory usage, but the Annif projects using the omikuji backend need to be retrained. The projects using other backends should not require retraining, although warnings may be shown in some cases.

The support for Python 3.6 is removed, which is necessitated by the dependency upgrades.

This release also removes the Maui and vw_multi (Vowpal Wabbit) backends.


New features:
374/527/563 spaCy analyzer

Improvements:
514/544 Optimize startup time using local & lazy imports
548 Allow selecting installed optional dependencies in Docker build
545/558 Select metrics for eval command using an option
546/557 Output eval metrics as a JSON file compatible with DVC

Bug fixes:
552/554 LMDB can overflow (credit: mo-fu)
562 Add missing import of annif.eval in MLLM backend

Maintenance:

This release includes a new [language filtering](https://github.com/NatLibFi/Annif/wiki/Transforms#filter_lang-transform) feature. This input-transform filters out sentences of the intput text whose language is different than the project language. The language detection is performed with [Compact Language Detector v3](https://github.com/google/cld3) via [`pycld3`](https://pypi.org/project/pycld3/). `pycld3` is an optional dependency of Annif, see the [installation page](https://github.com/NatLibFi/Annif/wiki/Optional-features-and-dependencies#language-filtering-with-pycld3).

Also minor bug fixes and dependency updates are included.

The [Maui](https://github.com/NatLibFi/Annif/wiki/Backend%3A-Maui) and [vw_multi](https://github.com/NatLibFi/Annif/wiki/Backend%3A-vw_multi) (Vowpal Wabbit) backends have been marked as deprecated in this release and they will be removed in the next release 0.56. Removing is motivated by making codebase more compact and thus easier to maintain. The [MLLM](https://github.com/NatLibFi/Annif/wiki/Backend%3A-MLLM) and [nn_ensemble](https://github.com/NatLibFi/Annif/wiki/Backend%3A-nn_ensemble) backends offer similar functionality as Maui and vw_multi.

Note that the notes for the previous release ([Annif 0.54](https://github.com/NatLibFi/Annif/releases/tag/v0.54.0)) initially missed to mention the added support for the [input-transform](https://github.com/NatLibFi/Annif/wiki/Transforms) feature.


New features:
464/507 Language filtering in input text

Improvements:
536 Allow rdflib version 6.*

Bug fixes:
533/534 Adjust flask and click versions to avoid dependency mismatches

Maintenance:
530 Add deprecation warning to Maui & vw_multi train commands
492/529 Update Docker base image to Debian Bullseye to upgrade Voikko library

This is a patch release that fixes bugs surfaced and found after 0.54.0 release. In particular, installation using pip was not working correctly due to a missing dependency on the dateutil package.

Bugs fixed:
523 Make Drone builds start on all git tag events
524 Add MLLM classifier sanity check
525 Much faster updating of existing large vocabulary
528 Declare dateutil dependency

This release adds a new `--jobs` parameter for the `annif train` command, which allows easy control of the number of threads/CPUs when training MLLM, fasttext and Omikuji backends. Many other improvements are included that speed up the MLLM backend, especially in the case of a large vocabulary. Also a few minor bugs have been fixed.

**Edit:** Also introduces support for adding new text-input transformation operations to Annif. Previously the input-limiting feature was implemented as a backend mechanism (446, 452), which was set up in a project configuration e.g. with a setting `input_limit=5000`; now the input-limiting feature is implemented as a more general input-text transform and it can be set up in the project configuration with `transform=limit(5000)`.

New features:
512 Support jobs parameter in train command
**Edit:** 496 Support for adding input-transformation operations

Improvements:
500 Implement custom MeanLayer in nn_ensemble
511/483 Process training docs in parallel in MLLM backend
513/519 Keep serialized dump of SKOS graph to save parsing time
518 Use least frequent token as key in TokenSetIndex used by MLLM
520 Optimize limit_mask creation

Bug fixes:
510/502 Use set as container of uris instead of list in DocumentFile
515/453 Allow NN ensemble to be used for parallel eval
517 Skip unimportant subjects in _vector_to_list_suggestion
522/521 Allow private projects to be accessed from CLI

This patch release includes the following changes:
- 506 Fix NN ensemble training and learning on one-document corpus
- 509 Warn instead of error in case of multiple subjects per doc in SVC training
- 503 Fix read-the-docs documentation build error due to package conflict