Update assertJ to newer version (by removing version override)

Author: cowtowncoder

avro/pom.xml

@@ -58,12 +58,9 @@ abstractions.
       <scope>test</scope>
     </dependency>
     <!-- For validating more complex comparisons -->
-    <!-- 27-Feb-2017, tatu: NOTE! Can NOT use 3.x as it requires Java 8 
-      -->
     <dependency>
       <groupId>org.assertj</groupId>
       <artifactId>assertj-core</artifactId>
-      <version>2.5.0</version>
       <scope>test</scope>
     </dependency>
   </dependencies>