Bump version to 2.2.1

Change-Id: Ia438d22b0f6ea4cc8f4db72f76284756382c764b
diff --git a/pom.xml b/pom.xml
index 61e763b..6de1181 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
 
     <groupId>groupId</groupId>
     <artifactId>totalngrams</artifactId>
-    <version>2.2.0</version>
+    <version>2.2.1</version>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>