ci: add format check to GitHub Actions workflow

Author: uwla

.github/workflows/tests.yml renamed to .github/workflows/ci.yml

@@ -1,4 +1,4 @@
-name: Automated tests
+name: CI
 
 on:
   push:
@@ -23,5 +23,6 @@ jobs:
         node-version: ${{ matrix.node-version }}
         cache: 'npm'
     - run: npm install
+    - run: npm run format:check
     - run: npm run build
     - run: npm run test