Set up a configuration for dependabot (#13671)

Author: brettcannon

.github/dependabot.yml

@@ -0,0 +1,21 @@
+version: 2
+updates:
+  - package-ecosystem: 'github-actions'
+    directory: /
+    schedule:
+      interval: daily
+
+  - package-ecosystem: 'pip'
+    directory: /
+    schedule:
+      interval: daily
+
+  - package-ecosystem: 'pip'
+    directory: /news
+    schedule:
+      interval: monthly
+  # Activate when we feel ready to keep up with frequency.
+  # - package-ecosystem: 'npm'
+  #   directory: /
+  #   schedule:
+  #     interval: daily