PR summary

• Why is this change necessary?

Unit test coverage for GTK (both v3 and v3) in our GitHub Actions CItests.yml workflow is largely skipped at the moment.

This is because recent versions ofPyGObject -- as required forimport gi to succeed -- are incompatible with thegirepository-1.0 system dependency that we install on our Ubuntu 22.04 runners.

Specifically, as noted in#29844,PyGObject v3.52 adds a requirement ongirepository-2.0.

The goal here is to re-enable GTK-related test coverage.

• What problem does it solve?

To work around the problem, this pull request suggests pinning the upper-bound version of thePyGObject library that we install on the affected Ubuntu 22.04 runners.

• What is the reasoning for this implementation?

1. Thegirepository-2.0 system dependency is unavailable on Ubuntu 22.04 (jammy) and may not become available on that OS version.

2. We have existing test coverage ofPyGObject v3.52 on Ubuntu 24.04withgirepository-2.0 - so my reasoning (also describedhere) is that retaining coverage ofgirepository-1.0 is worthwhile.

PR checklist

• "closes #0000" is in the body of the PR description tolink the related issue
• new and changed code is (will be, in this case)tested
• [N/A]Plotting related features are demonstrated in anexample
• [N/A]New Features andAPI Changes are noted with adirective and release note
• [N/A] Documentation complies withgeneral anddocstring guidelines

Resolves#29844.

Edit: attempt to clarify the nature of the problem that is being solved by this.
Edit: plurality fixup
Edit: rephrase description again.
Edit: clarify that this may not be a temporary fix (girepository-2.0 may not become available on Ubuntu 22.04).