Bump objenesis from 2.1 to 2.6

Bumps [objenesis](https://github.com/easymock/objenesis) from 2.1 to 2.6.
- [Release notes](https://github.com/easymock/objenesis/releases)
- [Commits](easymock/objenesis@2.1...2.6)

---
updated-dependencies:
- dependency-name: org.objenesis:objenesis
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -152,7 +152,7 @@
         <dependency> <!-- enables mocking of classes without default constructor (together with CGLIB) -->
             <groupId>org.objenesis</groupId>
             <artifactId>objenesis</artifactId>
-            <version>2.1</version>
+            <version>2.6</version>
             <scope>test</scope>
         </dependency>