add github workflow for checking code formatting

.github/workflows/lint.yml

@@ -0,0 +1,13 @@
+name: prettier check
+on: [push, pull_request]
+jobs:
+  lint:
+    name: Check for code formatting mistakes
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: '16'
+      - run: npm install
+      - run: npm run lint