Pin i18n-check to a version that works

Author: pamelafox

.github/workflows/python-test.yaml

@@ -50,7 +50,7 @@ jobs:
             npm install
             npm run build
         - name: Check i18n translations
-          run: npx -y @lingual/i18n-check --locales app/frontend/src/locales -s en -f i18next -r summary
+          run: npx -y @lingual/i18n-check@0.8.12 --locales app/frontend/src/locales -s en -f i18next -r summary
         - name: Install dependencies
           run: |
             uv pip install -r requirements-dev.txt