Show diff on pre-commit failure in CI (#133)

Author: coretl

template/pyproject.toml.jinja

@@ -94,7 +94,7 @@ allowlist_externals =
 {% if sphinx %}    sphinx-build
     sphinx-autobuild
 {% endif %}commands =
-    pre-commit: pre-commit run --all-files {posargs}
+    pre-commit: pre-commit run --all-files --show-diff-on-failure {posargs}
     type-checking: {{ type_checker }} src tests {posargs}
     tests: pytest --cov={{ package_name }} --cov-report term --cov-report xml:cov.xml {posargs}
 {% if sphinx %}    docs: sphinx-{posargs:build -EW --keep-going} -T docs build/html