feat: add Docker and Docker Compose to dependabot configuration

- Add Docker package ecosystem to track base image updates
- Add Docker Compose package ecosystem to track service dependencies
- Maintain same weekly schedule and labeling conventions

Author: kjanat

.github/dependabot.yml

@@ -16,6 +16,38 @@ updates:
       prefix: 'ci'
       include: 'scope'
 
+  # Check for updates to Docker
+  - package-ecosystem: 'docker'
+    directory: '/'
+    schedule:
+      interval: 'weekly'
+      day: 'monday'
+      time: '07:00'
+      timezone: 'Europe/Amsterdam'
+    open-pull-requests-limit: 10
+    labels:
+      - 'dependencies'
+      - 'docker'
+    commit-message:
+      prefix: 'docker'
+      include: 'scope'
+
+  # Check for updates to Docker Compose
+  - package-ecosystem: 'docker-compose'
+    directory: '/'
+    schedule:
+      interval: 'weekly'
+      day: 'monday'
+      time: '07:00'
+      timezone: 'Europe/Amsterdam'
+    open-pull-requests-limit: 10
+    labels:
+      - 'dependencies'
+      - 'docker-compose'
+    commit-message:
+      prefix: 'docker'
+      include: 'scope'
+
   # Check for updates to Go modules
   - package-ecosystem: 'gomod'
     directory: '/'