Context

In PYTHON-5328 I had to manually update the lock file, since uv lock's a hash on the branch for a git dependency.  It seems we cannot use a lock file for this installation.  Instead we can use a pip install in setup_tests.py to install from the pymongocrypt branch.

Definition of done

Update installation of pymongocrypt for tests.

• Update setup_tests.py
• Update pyproject.toml
• Update uv.lock

Pitfalls

None