[WIP] Fix CI

[Lonami]

(Please squash this into a single commit - a lot were made for testing).

Now I'm stuck here and I can't seem to figure this one out:

Error log "Missing 'Version:' header and/or PKG-INFO file"

Building cp36-macosx_x86_64 wheel
CPython 3.6 macOS x86_64

Installing Python cp36...
  
  + Download https://www.python.org/ftp/python/3.6.8/python-3.6.8-macosx10.9.pkg to /tmp/Python.pkg
  + sudo installer -pkg /tmp/Python.pkg -target /
  installer: Package name is Python
  installer: Upgrading at base path /
  installer: The upgrade was successful.
  + sudo /Library/Frameworks/Python.framework/Versions/3.6/bin/python3 /Users/runner/hostedtoolcache/Python/3.9.6/x64/lib/python3.9/site-packages/cibuildwheel/resources/install_certifi.py
  The directory '/Users/runner/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
  The directory '/Users/runner/Library/Caches/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
  Collecting certifi
    Downloading https://files.pythonhosted.org/packages/05/1b/0a0dece0e8aa492a6ec9e4ad2fe366b511558cdc73fd3abc82ba7348e875/certifi-2021.5.30-py2.py3-none-any.whl (145kB)
  /Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_internal/req/req_install.py:339: UserWarning: Unbuilt egg for Unknown [unknown version] (/Users/runner/work/cryptg/cryptg)
    self.satisfied_by = pkg_resources.get_distribution(str(no_marker))
  Exception:
  Traceback (most recent call last):
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2570, in version
      return self._version
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2677, in __getattr__
      raise AttributeError(attr)
  AttributeError: _version
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_internal/cli/base_command.py", line 143, in main
      status = self.run(options, args)
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_internal/commands/install.py", line 349, in run
      self._warn_about_conflicts(to_install)
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_internal/commands/install.py", line 475, in _warn_about_conflicts
      package_set, _dep_info = check_install_conflicts(to_install)
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_internal/operations/check.py", line 98, in check_install_conflicts
      package_set = create_package_set_from_installed()
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_internal/operations/check.py", line 41, in create_package_set_from_installed
      package_set[name] = PackageDetails(dist.version, dist.requires())
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2575, in version
      raise ValueError(tmpl % self.PKG_INFO, self)
  ValueError: ("Missing 'Version:' header and/or PKG-INFO file", Unknown [unknown version] (/Users/runner/work/cryptg/cryptg))
  You are using pip version 18.1, however version 21.2.4 is available.
  You should consider upgrading via the 'pip install --upgrade pip' command.
   -- pip install --upgrade certifi
  Traceback (most recent call last):
    File "/Users/runner/hostedtoolcache/Python/3.9.6/x64/lib/python3.9/site-packages/cibuildwheel/resources/install_certifi.py", line 55, in <module>
      main()
    File "/Users/runner/hostedtoolcache/Python/3.9.6/x64/lib/python3.9/site-packages/cibuildwheel/resources/install_certifi.py", line 32, in main
      [sys.executable, "-E", "-s", "-m", "pip", "install", "--upgrade", "certifi"]
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/subprocess.py", line 311, in check_call
      raise CalledProcessError(retcode, cmd)
  subprocess.CalledProcessError: Command '['/Library/Frameworks/Python.framework/Versions/3.6/bin/python3', '-E', '-s', '-m', 'pip', 'install', '--upgrade', 'certifi']' returned non-zero exit status 2.
Error: Command ['sudo', '/Library/Frameworks/Python.framework/Versions/3.6/bin/python3', '/Users/runner/hostedtoolcache/Python/3.9.6/x64/lib/python3.9/site-packages/cibuildwheel/resources/install_certifi.py'] failed with code 1. None

• The removal of tiny-AES is due to warnings.
• The introduction of pyproject.toml seems to make cibuildwheel Just Work™ (or at least, get closer).
• 0.2 of grammers-crypto was failing so I bumped that up, and PyO3 while I was at it.
• I'll revert the on: push once this is working.
• The env.CIBW changes are stolen inspired from the Rust projects at https://cibuildwheel.readthedocs.io/en/stable/working-examples/.
• I bumped cibuildwheel just in case.