… circular dependence

The new ``build+check+deploy`` workflow
  - builds wheels on Linux & macOS;
  - installs the wheels and runs the checks them;
  - deploys the wheels to PyPI (if running on a tagged commit).

The new ``build-doc+deploy-doc`` workflow
  - builds the package on Linux;
  - installs the package w/o a wheel;
  - builds the documentations;
  - deploys the documentation to pypmc.github.io (if running on a tagged commit)