Enable dependabot (#2963)

.github/dependabot.yml

@@ -0,0 +1,15 @@
+version: 2
+updates:
+  # Maintain dependencies for NPM
+  - package-ecosystem: npm
+    directory: "/"
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 10
+
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 10