Fix po filename in test-translations.yml

Author: rffontenelle

.github/workflows/test-translations.yml

@@ -71,4 +71,4 @@ jobs:
       run: nox -s build -- -q -D language=${{ matrix.language }}
 
     - name: Lint translation file
-      run: sphinx-lint locales/${{ matrix.language }}/LC_MESSAGES/message.po
+      run: sphinx-lint locales/${{ matrix.language }}/LC_MESSAGES/messages.po