[kv-interface] Update to version 1.2.1.

Author: wangzk

java/kvstore-interface/pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>cn.edu.nju.pasalab</groupId>
     <artifactId>kvstore-interface</artifactId>
-    <version>1.2-SNAPSHOT</version>
+    <version>1.2.1-SNAPSHOT</version>
     <dependencies>
         <dependency>
             <groupId>com.google.guava</groupId>