Building prebuilt binary wheels for multiple platforms & multiple Python versions

[ttimasdf]

The major change of this PR is the improved Github Actions workflow to build binaries for multiple platforms, powered by cibuildwheel. Currently, it can build wheels on Python 3.6\~3.10 for:

• windows amd64/win32
• manylinux i686/x86_64
• macosx x86_64
• musllinux i686/x86_64

PyPy is obviously incompatible, other platforms supported by cibuildwheel(CIBW_BUILD, CIBW_SKIP - Options - cibuildwheel) is yet to be tested.

Also I added some (opinionated) quality-of-life improvements.

• Add SQLite source code downloader. An option SQLITE_VERSION in setup.py controls which sqlite version to compile against. This make the build progress more deterministic.
• Add .gitignore
• PEP 517 compliance. Necessary for building the project with other tools, e.g. cibuildwheels, build or tox.
  • Add pyproject.toml
  • Rename build_ext to build_dynamic, and renamed build_static to build_ext. So the binary package will be statically compiled.
• Use setuptools_scm for version handling, based on git tags.

[coleifer]

Sorry, definitely not interested.

[ttimasdf]

for those who may interest, the automated build script is at https://github.com/pysqlite3/pysqlite3

the wheels for Windows/macOS/Linux are available at

• PyPI: pysqlite-binary · PyPI install through pip install pysqlite-binary
• and github releases: https://github.com/pysqlite3/pysqlite3/releases/latest