fix: ratingservice uwsgi build issue

[daniel-sanche]

We are currently seeing a uwsgi issue when deploying the ratingservice:

I believe this issue comes down to python3.8 being removed from the Cloud Shell base image in favor of Python 3.9. This PR attempts to fix the issue by updating the ratingservice to use python39, and updates the uwsgi package

[conventional-commit-lint-gcf[bot]]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot https://conventionalcommits.org/

[github-actions[bot]]

You can also use the Stage Website Action if there were updates to the website.

Note: Open in Cloud Shell may not work properly if this PR contains changes to the custom Cloud Shell image

[minherz]

changes were already merged