Fix CI: Pin ruff version to stable 0.13.x in test fixture (#305)

The test was using ruff>=0.14 which is under active development,
 causing failures as new versions like 0.14.13 are released. This
 changes the fixture to use ruff>=0.13 (where 0.13.3 is the final
 release) and updates the expected version in the test accordingly.

.github/workflows/test.yml

@@ -174,7 +174,8 @@ jobs:
           version-file: __tests__/fixtures/pyproject-dependency-groups-with-env-marker/pyproject.toml
       - name: Correct version gets installed
         run: |
-          if [ "$RUFF_VERSION" != "0.14.11" ]; then
+          if [ "$RUFF_VERSION" != "0.13.3" ]; then
+            echo "Expected version 0.13.3 but got $RUFF_VERSION"
             exit 1
           fi
         env:

__tests__/fixtures/pyproject-dependency-groups-with-env-marker/pyproject.toml

@@ -7,7 +7,7 @@ requires-python = ">=3.12"
 
 [dependency-groups]
 dev = [
-    "ruff>=0.14 ; python_version >= '3.11'",
+    "ruff~=0.13 ; python_version >= '3.11'",
 ]
 
 [build-system]