chore(deps): enable automatic updates for GitHub Actions via Dependabot (#7)

* Update GitHub Actions in .github/workflows/containers.yml to use pinned hashes

* Add dependabot configuration for GitHub Actions

Author: skylenet

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+   - package-ecosystem: github-actions
+     directory: /
+     schedule:
+        interval: monthly
+     groups:
+        actions:
+           patterns:
+              - '*'