Add workflow to automate prettier running on main (#720)

.github/workflows/format.yml

@@ -0,0 +1,38 @@
+name: Reformat main
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+on:
+  push:
+    branches: [main]
+
+env:
+  FORCE_COLOR: 3
+  NEXT_TELEMETRY_DISABLED: 1
+
+jobs:
+  prettify:
+    name: Auto-prettify
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+      - name: Restore cached node_modules
+        uses: actions/cache@v2
+        with:
+          path: '**/node_modules'
+          key: ${{ runner.os }}-${{ matrix.node-version }}-nodemodules-${{ hashFiles('**/yarn.lock') }}
+      - name: Install missing dependencies
+        run: yarn install --prefer-offline --frozen-lockfile
+      - name: Run Prettier on web client
+        working-directory: web
+        run: yarn format
+      - name: Commit any Prettier changes
+        uses: stefanzweifel/git-auto-commit-action@v4
+        with:
+          commit_message: Auto-prettification
+          branch: ${{ github.head_ref }}