(split out from #33613)

This is a pip-installable package

python3 -m pip install git+https://github.com/sagemath/git-trac-command

... but it is best to be installed by the user in their system environment, not in SAGE_VENV.

For example, we want to make it available on Gitpod, in devcontainers, and the user-facing Sage Docker images.

In src/environment-dev.yml (#33740), it should be added as a pip: line. (This happens through #33613.)

Depends on #30363

Component: packages: optional

Branch/Commit: u/mkoeppe/pip_package_git_trac_command @ 31db9da

Issue created by migration from https://trac.sagemath.org/ticket/34524