skip RTD builds if no relevant changes occur (#17544)

* skip RTD builds if no relevant changes occur

ref: https://docs.readthedocs.com/platform/stable/build-customization.html#cancel-build-based-on-a-condition

* add docs requirements files

* Update bin/rtd-docs

Co-authored-by: Mike Fiedler <[email protected]>

* Apply suggestions from code review

---------

Co-authored-by: Mike Fiedler <[email protected]>

Author: ewdurbin

bin/rtd-docs

@@ -5,20 +5,32 @@ set -e
 set -x
 
 if [ "${READTHEDOCS_PROJECT}" = "warehouse" ]; then
+  if [ "$READTHEDOCS_VERSION_TYPE" = "external" ] && git diff --quiet origin/main -- docs/dev requirements/docs-dev.txt .readthedocs.yaml; then
+    echo "Nothing relevant changed, skipping build..."
+    exit 183;
+  fi
   pip install -r requirements/docs-dev.txt
   asdf reshim
   make -C docs/dev/ html
   mkdir _readthedocs && mv docs/dev/_build/html _readthedocs/html
 fi
 
 if [ "${READTHEDOCS_PROJECT}" = "docspypiorg" ]; then
+  if [ "$READTHEDOCS_VERSION_TYPE" = "external" ] && git diff --quiet origin/main -- docs/user requirements/docs-user.txt .readthedocs.yaml docs/mkdocs-user-docs.yml; then
+    echo "Nothing relevant changed, skipping build..."
+    exit 183;
+  fi
   pip install -r requirements/docs-user.txt
   asdf reshim
   mkdocs build -f docs/mkdocs-user-docs.yml
   mkdir _readthedocs && mv docs/user-site _readthedocs/html
 fi
 
 if [ "${READTHEDOCS_PROJECT}" = "blogpypiorg" ] || [ "${READTHEDOCS_PROJECT}" = "psf-warehouse-private" ]; then
+  if [ "$READTHEDOCS_VERSION_TYPE" = "external" ] && git diff --quiet origin/main -- docs/blog requirements/docs-blog.txt .readthedocs.yaml docs/mkdocs-blog.yml; then
+    echo "Nothing relevant changed, skipping build..."
+    exit 183;
+  fi
   pip install -r requirements/docs-blog.txt
   asdf reshim
   mkdocs build -f docs/mkdocs-blog.yml