Bump readme version

Author: Max Klyga

README.md

@@ -12,14 +12,14 @@ Add the following dependency to your pom.xml:
 <dependency>
     <groupId>io.getstream.client</groupId>
     <artifactId>stream-java</artifactId>
-    <version>3.1.7</version>
+    <version>3.1.8</version>
 </dependency>
 ```
 
 or in your build.gradle:
 
 ```gradle
-compile 'io.getstream.client:stream-java:3.1.7'
+compile 'io.getstream.client:stream-java:3.1.8'
 ```
 
 In case you want to download the artifact and put it manually into your project,