fix(security): enable Dependabot for Yarn

Signed-off-by: squat <lserven@gmail.com>

.github/dependabot.yml

@@ -17,3 +17,7 @@ updates:
     directory: "/"
     schedule:
       interval: "weekly"
+  - package-ecosystem: "npm"
+    directory: "/"
+    schedule:
+      interval: "weekly"