run dependabot on npm dependencies as well

.github/dependabot.yml

@@ -10,4 +10,12 @@ updates:
     # You don't need to specify `/.github/workflows` for `directory`. You can use `directory: "/"`.
     directory: "/"
     schedule:
-      interval: "weekly"
+      interval: "monthly"
+
+  # Enable version updates for npm
+  - package-ecosystem: "npm"
+    # Look for `package.json` and `lock` files in the `root` directory
+    directory: "/"
+    # Check the npm registry for updates every day (weekdays)
+    schedule:
+      interval: "monthly"