Update README with correct version

Author: rbygrave

README.md

@@ -18,7 +18,7 @@ A lightweight wrapper to the [JDK 11+ Java Http Client](http://openjdk.java.net/
 <dependency>
   <groupId>io.avaje</groupId>
   <artifactId>avaje-http-client</artifactId>
-  <version>1.9</version>
+  <version>1.8</version>
 </dependency>
 ```