Correct syntax of "Update README" action

.github/workflows/update_readme.yml

@@ -1,21 +1,24 @@
 name: Update README
-on: push # For testing
-#  push:
-#    branches: [master]
+on:
+  push:
+    branches: [master]
 jobs:
   build:
-    - name: Checkout
-      uses: actions/checkout@v1
-      with:
-        fetch-depth: 1
-    - name: Setup Python
-      uses: actions/setup-python@v1
-      with:
-        python-version: 3.x
-        architecture: x64
-    - name: Update README
-      run: python update_readme.py
-    - name: Publish README
-      uses: mikeal/publish-to-github-action@4e60bca
-      env:
-        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    runs-on: ubuntu-18.04
+    name: Update README
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v1
+        with:
+          fetch-depth: 1
+      - name: Setup Python
+        uses: actions/setup-python@v1
+        with:
+          python-version: 3.x
+          architecture: x64
+      - name: Update README
+        run: python update_readme.py
+      - name: Publish README
+        uses: mikeal/publish-to-github-action@4e60bca
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}