Bump mockito-core from 3.0.0 to 3.1.0 (#42)

Bumps [mockito-core](https://github.com/mockito/mockito) from 3.0.0 to 3.1.0.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v3.0.0...v3.1.0)

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

Author: dependabot-preview[bot]

build.gradle

@@ -53,7 +53,7 @@ dependencies {
 
     testCompile group: 'junit', name: 'junit', version: '4.12'
 
-    testCompile 'org.mockito:mockito-core:3.0.0'
+    testCompile 'org.mockito:mockito-core:3.1.0'
 }
 
 task sourcesJar(type: Jar, dependsOn: classes) {