Update GitHub actions via Dependabot

Author: frerich

.github/dependabot.yml

@@ -8,3 +8,8 @@ updates:
     directory: "/"  # Location of package manifests
     schedule:
       interval: "weekly"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      # Check for updates to GitHub Actions every week
+      interval: "weekly"