show any diff introduced by pre-commit during CI

Author: jepler

.github/workflows/build.yml

@@ -25,4 +25,4 @@ jobs:
     - name: Install pre-commit
       run: pip install pre-commit
     - name: Run pre-commit
-      run: pre-commit run --all-files
+      run: pre-commit run --all-files --show-diff-on-failure

build/action.yml

@@ -61,7 +61,7 @@ runs:
   - name: Pre-commit hooks
     shell: bash
     run: |
-      pre-commit run --all-files
+      pre-commit run --all-files --show-diff-on-failure
   - name: Install pytest
     shell: bash
     run: pip install pytest