chore: Only use dependabot for internal action updates (#662)

.github/dependabot.yml

@@ -11,6 +11,9 @@ updates:
     schedule:
       # Check for updates to GitHub Actions every weekday
       interval: "daily"
+    allow:
+      # Allow updates for internal actions
+      - dependency-name: "hashicorp/*"
 
   # Maintain dependencies for Go modules
   - package-ecosystem: "gomod"