chore: configure Dependabot maintenance

.github/dependabot.yml

@@ -1,14 +1,50 @@
+# Scheduled version updates. Security updates are managed separately by GitHub.
 version: 2
 updates:
-  - package-ecosystem: bundler
-    directory: /
+  - package-ecosystem: "bundler"
+    directory: "/"
     schedule:
-      interval: weekly
-  - package-ecosystem: docker
-    directory: /
+      interval: "weekly"
+      day: "wednesday"
+      time: "07:00"
+      timezone: "Europe/Berlin"
+    open-pull-requests-limit: 3
+    groups:
+      routine-updates:
+        applies-to: version-updates
+        patterns:
+          - "*"
+        update-types:
+          - minor
+          - patch
+  - package-ecosystem: "docker"
+    directory: "/"
     schedule:
-      interval: weekly
-  - package-ecosystem: github-actions
-    directory: /
+      interval: "weekly"
+      day: "wednesday"
+      time: "07:20"
+      timezone: "Europe/Berlin"
+    open-pull-requests-limit: 3
+    groups:
+      routine-updates:
+        applies-to: version-updates
+        patterns:
+          - "*"
+        update-types:
+          - minor
+          - patch
+  - package-ecosystem: "github-actions"
+    directory: "/"
     schedule:
-      interval: weekly
+      interval: "monthly"
+      time: "08:00"
+      timezone: "Europe/Berlin"
+    open-pull-requests-limit: 3
+    groups:
+      routine-updates:
+        applies-to: version-updates
+        patterns:
+          - "*"
+        update-types:
+          - minor
+          - patch