I'm evaluating workalendar and am put off by two GPL dependencies (lunardate and pyCalverter) that aren't relevant to my usage. GPL is blacklisted for this project, so I won't be able to use this library unless I can exclude them somehow.

From what I can see the mixins that use those dependencies (LunarMixin, CalverterMixin) are scattered throughout the library. Would you accept a pull request that wraps the import in a try and only defines the mxins if they're available? That way, I could at least uninstall the dependencies from my environment and the rest of the library would work.

On a longer-term level, maybe those libraries could be reimplemented from some codebase with a different license or the authors could be convinced to also use the LGPL license.