Add support for GitHub Actions in Dependabot config

https://docs.github.com/en/code-security/reference/supply-chain-security/dependabot-options-reference#directories-or-directory--

Author: nemchik

.github/dependabot.yml

@@ -1,6 +1,8 @@
 version: 2
 updates:
   - package-ecosystem: "github-actions"
-    directory: "/"
+    directories:
+      - "/"
+      - "/.github/actions/*/"
     schedule:
       interval: "daily"