Modernize build configuration

[jakob-keller]

Description of Change

• remove outdated MANIFEST.in -> gets rid of build warnings
• remove arguments include_package_data and packages to setup() -> gets rid of build issues around retries sub-package
• add PEP 517 / PEP 518 compatible [build-system] table to pyproject.toml
• add PEP 621 compatible [project] table to pyproject.toml and merge contents of setup.py into it
• update relevant documentation and unit tests

Assumptions

• Follows https://packaging.python.org/en/latest/guides/modernize-setup-py-project/ (shared by @webknjaz)
• setuptools is kept as build backend (for now)
• I have generated pre and post distribution artefacts locally using python -m build and confirmed that they are equivalent.

Checklist for All Submissions

• I have added change info to CHANGES.rst
• If this is resolving an issue (needed so future developers can determine if change is still necessary and under what conditions) (can be provided via link to issue with these details):
  • Detailed description of issue
  • Alternative methods considered (if any)
  • How issue is being resolved
  • How issue can be reproduced
• If this is providing a new feature (can be provided via link to issue with these details):
  • Detailed description of new feature
  • Why needed
  • Alternatives methods considered (if any)

Checklist when updating botocore and/or aiohttp versions

• I have read and followed CONTRIBUTING.rst
• I have updated test_patches.py where/if appropriate (also check if no changes necessary)
• I have ensured that the awscli/boto3 versions match the updated botocore version

[codecov]

Codecov Report

Attention: Patch coverage is 93.75000% with 1 line in your changes missing coverage. Please review.

Project coverage is 86.98%. Comparing base (2d9857b) to head (0d06dd2).
Report is 5 commits behind head on master.

Files	Patch %	Lines
tests/test_version.py	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1160      +/-   ##
==========================================
- Coverage   87.03%   86.98%   -0.05%     
==========================================
  Files          64       64              
  Lines        5969     5978       +9     
==========================================
+ Hits         5195     5200       +5     
- Misses        774      778       +4     

Flag	Coverage Δ
unittests	86.98% <93.75%> (-0.05%)	⬇️

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[thehesiod]

I think setuptools is going away no? I remember now using the build module

[jakob-keller]

Not really: setuptools is still fully supported and maintained - as a build backend, just not as a build tool. build is a build tool that support any compatible backend. The two work hand in hand.

I am working on modernizing our build and packaging setup, which will include switching the build tool to build, while keeping setuptools as backend, at least for now. Once that setup is modernised, it will be a lot easier to switch build backends and/or tools if we decide to do so.

[jakob-keller]

Thank you for reviewing, @thehesiod & @webknjaz!