Cymr

This version fixes a problem where extension modules were not installed correctly from `.c` files.

This version modernizes the build system and fixes an issue where installation from a source distribution would fail.

Summary of changes:
* Most setup options are now defined in `setup.cfg`.
* The `requirements.txt` file has been removed.
* The `upload.sh` script has been removed; uploading to PyPI is handled by a GitHub Workflow.
* Extensions are now either built from a `.pyx` file if available, or a `.c` file otherwise.

This version reverts the build system to Ubuntu and removes wheel building to avoid uploading error.

This version changes the Python build platform to macOS to avoid wheel creation problems and enhance installation performance on macOS machines.

This version adds a link to the Zenodo archive and attempts to fix a bug with automated publishing to PyPI.

This version adds support for automatically publishing releases to PyPI and Zenodo.