Configure dependabot to update GitHub actions

Author: vkucera

.github/dependabot.yml

@@ -1,6 +1,13 @@
-version: 2
+---
+# Dependabot configuration
+# Reference: https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
 
+version: 2
 updates:
+  - package-ecosystem: "github-actions" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"
   - package-ecosystem: "pip"
     directory: "/"
     schedule: