Store repo license again

[jhrozek]

Summary

We used to store repo license since
5a78abc but then stopping saving the
attribute in d68e8e6. We still have
ruletypes that rely on that attribute, so let's just re-add it.

Side-note: Saving generic attributes will get way easier once we
implement properties fully.

Change Type

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

manually

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[jhrozek]

hmm, it should be possible to write a unit test. I should add a test case, sorry!

[coveralls]

coverage: 53.935% (-0.002%) from 53.937%
when pulling 417c7e1 on jhrozek:license_attr
into 4083e3f on stacklok:main.