Bugfixes and `/api/v3/users/` endpoint changes

While doing routine maintenance to keep Django Packages updated #1156, we fixed a bug in the Python3 view page #1157.

We also noticed a legacy /api/v3/users/ endpoint that aggregates users with their GitHub and GitLab user accounts, generating some 500 errors in our Sentry logs.

This afternoon, we took a proactive stance by implementing authentication for our user REST endpoints #1158. We plan to discuss these REST endpoints in more detail with our project maintainers before we take the steps to fully remove them.

It's worth noting that there was no private data leakage, no passwords, and no emails leaked in these endpoints.

If you built a tool that depends on these REST endpoints, feel free to open a GitHub Issue, and we will consider your use case before we remove them.