Add dependabot (Azure#329)

Author: bfoley13

.github/dependabot.yml

@@ -0,0 +1,18 @@
+version: 2
+updates:
+   - package-ecosystem: npm
+     directory: /
+     schedule:
+        interval: weekly
+     groups:
+        actions:
+           patterns:
+              - '*'
+   - package-ecosystem: github-actions
+     directory: .github/workflows
+     schedule:
+        interval: weekly
+     groups:
+        actions:
+           patterns:
+              - '*'