chore: update dependabot.yml to include gha

Author: bdraco

.github/dependabot.yml

@@ -5,6 +5,16 @@
 
 version: 2
 updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+    commit-message:
+      prefix: "chore(deps-ci): "
+    groups:
+      github-actions:
+        patterns:
+          - "*"
   - package-ecosystem: "pip" # See documentation for possible values
     directory: "/" # Location of package manifests
     schedule: