run frontend linting in gh-actions

Author: ffreddow

.github/workflows/frontend-tests.yml

@@ -34,6 +34,10 @@ jobs:
       working-directory: ./frontend
       run: npm ci
 
+    - name: Run ESLint
+      working-directory: ./frontend
+      run: npm run lint
+
     - name: Run unit tests
       working-directory: ./frontend
       run: npm run test:unit:run