Update tests.yaml

Permettre le linting suivant un merge commit

.github/workflows/tests.yaml

@@ -35,5 +35,7 @@ jobs:
           pip install --constraint=.github/workflows/constraints.txt pre-commit black flake8 reorder-python-imports
 
       - name: Run pre-commit on all files
+        env:
+          SKIP: no-commit-to-branch
         run: |
           pre-commit run --all-files --show-diff-on-failure --color=always