Add JDK-11 check for gradle build

Author: admin

settings.gradle

@@ -5,3 +5,7 @@ include "axelor-gradle"
 include "axelor-test"
 include "axelor-core"
 include "axelor-web"
+
+if (JavaVersion.current() != JavaVersion.VERSION_11) {
+  throw new GradleException("This build requires JDK-11.")
+}