Add a test against the latest version of ruff available

This is a test added to the matrix of tests run by CI, but marked as
`continue-on-error` so that the full suite does not fail if this test
fails. The purpose is to signal that a later version of ruff may exist
that causes new linting/formatting failures, but allowing the dev team
to manually upgrade to the new version.

.github/workflows/backend-ci.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        tox-env: [lint, type, test, check-migrations]
+        tox-env: [lint, type, test, check-migrations, ruff-latest]
     services:
       postgres:
         image: postgres:latest
@@ -48,6 +48,7 @@ jobs:
           pip install --upgrade pip
           pip install tox
       - name: Run tests
+        continue-on-error: ${{ matrix.tox-env == 'ruff-latest' }}
         run: |
           tox -e ${{ matrix.tox-env }}
         env:

tox.ini

@@ -28,6 +28,16 @@ commands =
     ruff check --fix-only
     ruff format
 
+[testenv:ruff-latest]
+package = skip
+ignore_errors = True
+deps =
+    ruff
+commands =
+    ruff -V
+    ruff check
+    ruff format --check
+
 [testenv:type]
 deps =
     mypy