Fix Maven package version (docker-java#748)

Version `3.0.6` was released, current snapshot is `3.0.7-SNAPSHOT`

Author: ooxi

README.md

@@ -56,7 +56,7 @@ Supports a subset of the Docker Remote API [v1.23](https://github.com/docker/doc
     <dependency>
           <groupId>com.github.docker-java</groupId>
           <artifactId>docker-java</artifactId>
-          <version>3.0.3</version>
+          <version>3.0.6</version>
     </dependency>
 
 ### Latest development version
@@ -67,7 +67,7 @@ You can find the latest development version including javadoc and source files o
     <dependency>
           <groupId>com.github.docker-java</groupId>
           <artifactId>docker-java</artifactId>
-          <version>3.0.4-SNAPSHOT</version>
+          <version>3.0.7-SNAPSHOT</version>
     </dependency>