add: prettier CI

.github/workflows/prettier.yml

@@ -0,0 +1,22 @@
+name: Prettier CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+jobs:
+  prettier:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          ref: ${{ github.head_ref }}
+
+      - name: Prettify code
+        uses: creyD/prettier_action@v4.2
+        with:
+          prettier_options: --write **/*.{json,md} --use-tabs