Bump mockito-core from 2.27.0 to 2.28.1

Bumps [mockito-core](https://github.com/mockito/mockito) from 2.27.0 to 2.28.1.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](https://github.com/mockito/mockito/compare/v2.27.0...v2.28.1)

build.gradle

@@ -294,7 +294,7 @@ dependencies {
 
     // dependencies for local unit tests
     testImplementation 'junit:junit:4.12'
-    testImplementation 'org.mockito:mockito-core:2.27.0'
+    testImplementation 'org.mockito:mockito-core:2.28.1'
     testImplementation 'androidx.test:core:1.1.0'
     testImplementation 'org.powermock:powermock-core:2.0.2'
     testImplementation 'org.powermock:powermock-module-junit4:2.0.2'