Work around spell checking breakage on contractions

See https://github.com/sphinx-contrib/spelling/issues/37.

.gitlab-ci.yml

@@ -17,8 +17,8 @@ test:
     # Prevent versioning support from kicking in as that breaks
     # sphinx-build invocations.
     - unset CI
-    - sphinx-build -M linkcheck . _build/
     - sphinx-build -M spelling . _build/ -W --keep-going
+    - sphinx-build -M linkcheck . _build/
 
 pages:
   stage: publish