ignore jdk updates

Author: tboeghk

.github/dependabot.yml

@@ -3,6 +3,9 @@ version: 2
 updates:
   - package-ecosystem: "docker"
     directory: "/"
+    ignore:
+      - dependency-name: "openjdk"
+        versions: ["12.x", "13.x", "14.x", "15.x", "16.x"]
     schedule:
       interval: "weekly"
     open-pull-requests-limit: 5