Add missing test to workflow

Author: ahopkins

.github/workflows/tests.yml

@@ -37,6 +37,7 @@ jobs:
           - { python-version: "3.10", tox-env: py310,         max-attempts: 3 }
           - { python-version: "3.10", tox-env: py310-no-ext,  max-attempts: 3 }
           - { python-version: "3.11", tox-env: py311,         max-attempts: 3 }
+          - { python-version: "3.11", tox-env: py311-no-ext,  max-attempts: 3 }
           - { python-version: "3.12", tox-env: py312,         max-attempts: 3 }
           - { python-version: "3.12", tox-env: py312-no-ext,  max-attempts: 3 }
           - { python-version: "3.13", tox-env: py313,         max-attempts: 3 }