Make sphinx warnings fail CI

Author: LilSpazJoekp

.github/workflows/ci.yml

@@ -43,7 +43,7 @@ jobs:
     - name: Run pydocstyle
       run: pydocstyle praw
     - name: Run sphinx
-      run: sphinx-build --keep-going docs/ /tmp/foo
+      run: sphinx-build -W --keep-going docs/ /tmp/foo
     strategy:
       matrix:
         os: [macOS-latest, ubuntu-latest, windows-latest]