Release rules_python 1.3

[mollyibot]

Can you do a release to include the recent change, the last release was over 3 weeks ago. Thanks

[rickeylev]

Hi again :)

Once things are up and running again, we'll do a release. Everything is looking pretty good, but we need to fix our docs build first: #2680

This week turned particularly busy for both me and Ignas, though, so our time this week is less than usual.

[rickeylev]

1.3.0-rc1 is released. It'll be promoted to stable next week, pending feedback.