Smart-open

* Refactor Google Cloud Storage to use blob.open (__[ddelange](https://github.com/ddelange)__, [#744](https://github.com/RaRe-Technologies/smart_open/pull/744))
* Add FTP/FTPS support (33) (__[RachitSharma2001](https://github.com/RachitSharma2001)__, [#739](https://github.com/RaRe-Technologies/smart_open/pull/739))
* Bring back compression_wrapper(filename) + use case-insensitive extension matching (__[piskvorky](https://github.com/piskvorky)__, [#737](https://github.com/RaRe-Technologies/smart_open/pull/737))
* Fix avoidable S3 race condition (693) (__[RachitSharma2001](https://github.com/RachitSharma2001)__, [#735](https://github.com/RaRe-Technologies/smart_open/pull/735))
* setup.py: Remove pathlib2 (__[jayvdb](https://github.com/jayvdb)__, [#733](https://github.com/RaRe-Technologies/smart_open/pull/733))
* Add flake8 config globally (__[cadnce](https://github.com/cadnce)__, [#732](https://github.com/RaRe-Technologies/smart_open/pull/732))
* Added buffer_size parameter to http module (__[mullenkamp](https://github.com/mullenkamp)__, [#730](https://github.com/RaRe-Technologies/smart_open/pull/730))
* Added documentation to support GCS anonymously (__[cadnce](https://github.com/cadnce)__, [#728](https://github.com/RaRe-Technologies/smart_open/pull/728))
* Reconnect inactive sftp clients automatically (__[Kache](https://github.com/Kache)__, [#719](https://github.com/RaRe-Technologies/smart_open/pull/719))

- Fix quadratic time ByteBuffer operations (PR [711](https://github.com/RaRe-Technologies/smart_open/pull/711), [Joshua-Landau-Anthropic](https://github.com/Joshua-Landau-Anthropic))

- Add cert parameter to http transport params (PR [703](https://github.com/RaRe-Technologies/smart_open/pull/703), [stev-0](https://github.com/stev-0))
- Allow passing additional kwargs for Azure writes (PR [702](https://github.com/RaRe-Technologies/smart_open/pull/702), [ddelange](https://github.com/ddelange))

This release deprecates the old `ignore_ext` parameter.
Use the `compression` parameter instead.

python
fin = smart_open.open("/path/file.gz", ignore_ext=True) No
fin = smart_open.open("/path/file.gz", compression="disable") Yes

fin = smart_open.open("/path/file.gz", ignore_ext=False) No
fin = smart_open.open("/path/file.gz") Yes
fin = smart_open.open("/path/file.gz", compression="infer_from_extension") Yes, if you want to be explicit

fin = smart_open.open("/path/file", compression=".gz") Yes


- Make Python 3.7 the required minimum (PR [688](https://github.com/RaRe-Technologies/smart_open/pull/688), [mpenkov](https://github.com/mpenkov))
- Drop deprecated ignore_ext parameter (PR [661](https://github.com/RaRe-Technologies/smart_open/pull/661), [mpenkov](https://github.com/mpenkov))
- Drop support for passing buffers to smart_open.open (PR [660](https://github.com/RaRe-Technologies/smart_open/pull/660), [mpenkov](https://github.com/mpenkov))
- Support working directly with file descriptors (PR [659](https://github.com/RaRe-Technologies/smart_open/pull/659), [mpenkov](https://github.com/mpenkov))
- Added support for viewfs:// URLs (PR [665](https://github.com/RaRe-Technologies/smart_open/pull/665), [ChandanChainani](https://github.com/ChandanChainani))
- Fix AttributeError when reading passthrough zstandard (PR [658](https://github.com/RaRe-Technologies/smart_open/pull/658), [mpenkov](https://github.com/mpenkov))
- Make UploadFailedError picklable (PR [689](https://github.com/RaRe-Technologies/smart_open/pull/689), [birgerbr](https://github.com/birgerbr))
- Support container client and blob client for azure blob storage (PR [652](https://github.com/RaRe-Technologies/smart_open/pull/652), [cbare](https://github.com/cbare))
- Pin google-cloud-storage to >=1.31.1 in extras (PR [687](https://github.com/RaRe-Technologies/smart_open/pull/687), [PLPeeters](https://github.com/PLPeeters))
- Expose certain transport-specific methods e.g. to_boto3 in top layer (PR [664](https://github.com/RaRe-Technologies/smart_open/pull/664), [mpenkov](https://github.com/mpenkov))
- Use pytest instead of parameterizedtestcase (PR [657](https://github.com/RaRe-Technologies/smart_open/pull/657), [mpenkov](https://github.com/mpenkov))

- make HTTP/S seeking less strict (PR [646](https://github.com/RaRe-Technologies/smart_open/pull/646), [mpenkov](https://github.com/mpenkov))

- Work around changes to `urllib.parse.urlsplit` (PR [633](https://github.com/RaRe-Technologies/smart_open/pull/633), [judahrand](https://github.com/judahrand))
- New blob_properties transport parameter for GCS (PR [632](https://github.com/RaRe-Technologies/smart_open/pull/632), [FHTheron](https://github.com/FHTheron))
- Don't leak compressed stream (PR [636](https://github.com/RaRe-Technologies/smart_open/pull/636), [ampanasiuk](https://github.com/ampanasiuk))
- Change python_requires version to fix PEP 440 issue (PR [639](https://github.com/RaRe-Technologies/smart_open/pull/639), [lucasvieirasilva](https://github.com/lucasvieirasilva))
- New max_concurrency transport parameter for azure (PR [642](https://github.com/RaRe-Technologies/smart_open/pull/642), [omBratteng](https://github.com/omBratteng))