create python package tag

[dboghrat]

Add a tag in the keywords search for our python packages.

[egrace479]

Tags are pulled from the repos themselves. Is this a case where we should have something like pypi-package or just pypi as a keyword in the repos themselves when we add them, or do we want another filter?

[hlapp]

Indeed, @dboghrat can you clarify what the actual use-case is? "I want to search for Pypi-released python packages", or "I want to search for python software" or yet something else?