Log Message:
Update to 0.23

Upstream changes:
0.23 2021-05-31
- added CI - thanks @zmughal
- now recognises MacOS clang - thanks @xenu

0.22 2021-05-29
- Add C++ standard support flag detection - thanks @zmughal!
  See <https://github.com/tsee/extutils-cppguess/pull/24>.