Macos support

[aligfellow]

Addresses #19.

python/setup.py: detect X11 paths at build time on macOS via pkg-config, falling back to known Homebrew prefixes (/opt/homebrew, /usr/local).

.github/workflows/wheels.yml: add macos-latest to the build. Uses CIBW_BEFORE_ALL_MACOS to install required libs via brew. Sets MACOSX_DEPLOYMENT_TARGET to match the X11 libs on the runner. Added workflow_dispatch so the build can be triggered manually from the GitHub actions tab.

.github/workflows/release.yml: add macos-latest to the build matrix so that v binary is also built on macOS for GitHub releases. Publish job uses wildcard so that both Linux and macOS wheels are uploaded to PyPI.

Mac installation looks something like this:

• we require an X11 server like XQuartz for running

  brew install --cask xquartz # runtime display 
  pip install vmol            # installed from wheels on pypi

• this can also be installed from source, though this required the libraries for installation

  brew install --cask xquartz # runtime display 
  brew install libx11 libxpm pkg-config 
  pip install "git+https://github.com/briling/v.git#subdirectory=python"