Use re-usable workflow for GitHub CI once gooey package is available on conda-forge

[bobleesj]

Problem

In test-on-pr and matrix CI, we pip install gooey as shown below:

      - name: Install regolith and requirements
        run: |
          conda install --file requirements/test.txt
          conda install --file requirements/conda.txt
          pip install gooey
          python -m pip install . --no-deps

Proposed solution

Once gooey is available as a conda-package, we can add gooey back to conda.txt and then use the BG's reusable .yml script.