ci: improve dependabot config for github actions

Signed-off-by: Emilien Escalle <[email protected]>

Author: neilime

.github/dependabot.yml

@@ -26,7 +26,9 @@ updates:
           - "*"
 
   - package-ecosystem: github-actions
-    directory: "/"
+    directories:
+      - "/"
+      - "/.github/workflows/actions/**/*"
     schedule:
       interval: weekly
       day: friday