Try to fix CI git error

When attempting to run the pre-commit hooks in the CI, we get this
error:

An error has occurred: FatalError: git failed. Is it installed, and are you in a Git repository directory?

actions/checkout#766 suggests the issue could
be because 'actions/checkout' clones the repository as a different user
than is used in our custom docker container. Git then doesn't trust the
repository and errors when called upon.

.github/workflows/ci.yml

@@ -17,6 +17,10 @@ jobs:
     - uses: actions/checkout@v3
     - name: Quality Checks
       run: |
+        # As we're running in our own container, we're not the same user as is
+        # used by 'actions/checkout', so git operations fail.
+        # https://github.com/actions/checkout/issues/766
+        git config --global --add safe.directory "$GITHUB_WORKSPACE"
         pip install pre-commit
         pre-commit install
         pre-commit run --all