fix command

Author: molpopgen

.github/workflows/black.yml

@@ -36,6 +36,6 @@ jobs:
           uv sync --only-group format
       - name: Validate code
         run: |
-          find fwdpy11 tests tests_with_cpp examples -name '*.py' | xargs python -m black --check
+          find fwdpy11 tests tests_with_cpp examples -name '*.py' | grep -v headers | grep -v demes-spec | xargs python -m black --check