Bump hamcrest-core from 1.3 to 2.1

Bumps [hamcrest-core](https://github.com/hamcrest/JavaHamcrest) from 1.3 to 2.1.
- [Release notes](https://github.com/hamcrest/JavaHamcrest/releases)
- [Changelog](https://github.com/hamcrest/JavaHamcrest/blob/master/CHANGES.md)
- [Commits](hamcrest/JavaHamcrest@hamcrest-java-1.3...v2.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-preview[bot]

build.gradle

@@ -34,7 +34,7 @@ dependencies {
 
     testCompile group: 'junit', name: 'junit', version: '4.12'
     testCompile group: 'org.mockito', name: 'mockito-core', version: '3.0.0'
-    testCompile group: 'org.hamcrest', name: 'hamcrest-core', version: '1.3'
+    testCompile group: 'org.hamcrest', name: 'hamcrest-core', version: '2.1'
 }
 
 processResources {