Merge pull request #551 from freifunkMUC/backport-460-to-gluon-v2023.2.x

[Backport gluon-v2023.2.x] Create dependabot.yml and reduce dependabot interval

.github/dependabot.yml

@@ -0,0 +1,12 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://help.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      # Check for updates to GitHub Actions once a week
+      interval: "weekly"