chore: add dependabot weekly update config (#205)

chore: add standardized dependabot config

Weekly Sunday 22:00 UTC, 5 PR limit per ecosystem, minor+patch grouped.

Signed-off-by: Thomas Müller <1005065+DeepDiver1975@users.noreply.github.com>

Author: DeepDiver1975

.github/dependabot.yml

@@ -0,0 +1,29 @@
+version: 2
+updates:
+  - package-ecosystem: composer
+    directory: "/"
+    schedule:
+      interval: weekly
+      day: sunday
+      time: '22:00'
+      timezone: Etc/UTC
+    open-pull-requests-limit: 5
+    groups:
+      minor-and-patch:
+        update-types:
+          - minor
+          - patch
+
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: weekly
+      day: sunday
+      time: '22:00'
+      timezone: Etc/UTC
+    open-pull-requests-limit: 5
+    groups:
+      minor-and-patch:
+        update-types:
+          - minor
+          - patch