Add Dependabot scanning (#14238)

* Update main.yml

* Create dependabot.yml

.github/dependabot.yml

@@ -0,0 +1,13 @@
+version: 2
+updates:
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+
+  # Maintain dependencies for Python
+  - package-ecosystem: "pip"
+    directory: "/"
+    schedule:
+      interval: "daily"

.github/workflows/main.yml

@@ -6,7 +6,7 @@ jobs:
   lint:
     runs-on: ubuntu-18.04
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - uses: actions/setup-python@v1
         with:
           python-version: '3.7'