Liara

* Add support for parallel node processing. This can result in significantly faster build times for sites with many resources. You can use ``--no-parallel`` to disable parallel processing in case this causes problems.
* Add support for additional thumbnail formats. This also replaces the old mechanism using ``image_thumbnail_sizes`` with a new configuration setting, ``image_thumbnails``.
* Use ``tomllib`` on Python 3.11 instead of ``tomli``.
* The `RedisCache` uses transactions now to avoid problems with concurrent access to individual cache items.

* Add `Query.with_node_kinds` and `Query.without_node_kinds` to `Query`. This allows lists of nodes (as returned by `SiteTemplateProxy.select` and other functions) to be filtered by the node kind. This is useful if you want to mix static content and documents in the same folder.
* Add `SiteTemplateProxy.select_pages` and `Page.children` to select pages (i.e. document and index nodes) only without having to manually filter the result using `with_node_kinds`/`without_node_kinds`.
* Add `node_kinds` to `Collection.__init__` to allow constraining a collection to a specific node kind.
* Add `exclude_without` to `Collection.__init__` and `Index.__init__` to allow excluding items without a specific metadata field.
* Improve the debug output during publishing. The template publisher will now print which document is published using which template. As part of this change, `Template.path` was added.
* Change how `Page.references` is populated for *top level indices*. Previously, ``references`` would not be populated for a top-level index. Additionally, improve the documentation of top-level indices.
* Improve error handling when trying to sort nodes which are missing the corresponding metadata key, for example, using `liara.query.Query.sorted_by_title`. Previously, this would raise an exception about a failed comparison involving `None`, now this raises a more useful exception which contains the path to the item missing the metadata key and which key was requested.

* Add a new configuration option to select the SASS compiler.
* Add support for caching to `SassResourceNode`. This can significantly speed up building sites with large amounts of SASS files.
* Change the default log formatting settings:
* The default output no longer includes the source. The source refers (typically) to the class producing the log message and results in noise for most normal use of Liara.
* The verbose output includes the message severity now. This makes it easier to spot warnings and errors in the verbose output.
* The debug output level contains both the source and the severity.

* Improve error handling during publishing. A generated node that fails to produce content is now skipped and a warning is printed.
* Non-fatal issues (i.e. those which don’t stop the build) use the warning log level now instead of error.
* Update `PyYAML` dependency to 6.0.
* Update `pymdown-extensions` dependency to 9.0.
* Replace `toml` dependency with `tomli` which is TOML 1.0 compliant (`toml` only supports TOML 0.5)
* Add Python 3.10 as an officially supported version.

* Add a new `--date` option to the command line to build the site at a different date. This is useful conjunction with the `DateFilter`, as it allows previewing scheduled entries.
* Improve error handling during content discovery. An error while creating a document will no longer abort the build. Additionally, instead of printing a full stack trace, an short error message containing the file path is printed. In any case, discovery continues so multiple broken documents can be identified.

* Improve ambiguous template pattern resolution.
* Allow setting template backend options. As part of this change, the Jinja2 backend now sets `trim_blocks` and `lstrip_blocks` by default to `True`.