update gitlab CI (replace deprecated docker image)

.gitlab-ci.yml

@@ -5,13 +5,13 @@ stages:
     - deploy
 
 test:
-    image: openjdk:21
+    image: eclipse-temurin:21-jammy
     stage: test
     script:
         - ./gradlew --continue --console=plain --info verifyPlugin
 
 jar:
-    image: openjdk:21
+    image: eclipse-temurin:21-jammy
     stage: jar
     script:
         - ./gradlew --continue --console=plain --info buildPlugin