Update build image java version

.gitlab-ci.yml

@@ -17,7 +17,7 @@ format-check:
 
 verify:
   stage: build
-  image: maven:3.6.3-jdk-11
+  image: maven:3.6.3-jdk-14
   script:
     - mvn checkstyle:check verify
     - awk -F"," '{ branches += $4 + $5 + $6 + $7; covered += $5 + $7 } END { print covered, "/", branches, "branches covered"; print 100*covered/branches, "%covered" }' target/site/jacoco/jacoco.csv