dependabot for docker

Signed-off-by: Jan Kowalleck <[email protected]>

.github/dependabot.yml

@@ -1,5 +1,4 @@
-# https://help.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
-
+# https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
 version: 2
 updates:
   - package-ecosystem: 'github-actions'
@@ -12,3 +11,13 @@ updates:
       prefix: 'chore'   ## prefix maximum string length of 15
       include: 'scope'
     open-pull-requests-limit: 999
+  - package-ecosystem: 'docker'
+    directory: '/'
+    schedule:
+      interval: 'weekly'
+      day: 'saturday'
+    labels: [ 'dependencies' ]
+    commit-message:
+      prefix: 'chore'   ## prefix maximum string length of 15
+      include: 'scope'
+    open-pull-requests-limit: 999