CI: Add spellcheck job

Author: effigies

.github/workflows/test.yml

@@ -168,7 +168,7 @@ jobs:
     continue-on-error: true
     strategy:
       matrix:
-        check: ['style', 'doctest', 'typecheck']
+        check: ['style', 'doctest', 'typecheck', 'spellcheck']
 
     steps:
       - uses: actions/checkout@v4