[hotfix][release] Add 1.16 to the flink versions enum

This closes apache#19097.

Author: gaoyunhaii

flink-annotations/src/main/java/org/apache/flink/FlinkVersion.java

@@ -52,7 +52,8 @@ public enum FlinkVersion {
     v1_12("1.12"),
     v1_13("1.13"),
     v1_14("1.14"),
-    v1_15("1.15");
+    v1_15("1.15"),
+    v1_16("1.16");
 
     private final String versionStr;