Make jruby still depend on beta-4

ruby/pom.xml

@@ -86,7 +86,7 @@
         <dependency>
             <groupId>com.google.protobuf</groupId>
             <artifactId>protobuf-java</artifactId>
-            <version>3.0.0</version>
+            <version>3.0.0-beta-4</version>
         </dependency>
     </dependencies>
 </project>