Bump mockito-core from 2.19.1 to 2.20.0 (#95)

Bumps [mockito-core](https://github.com/mockito/mockito) from 2.19.1 to 2.20.0.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v2.19.1...v2.20.0)

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

pom.xml

@@ -76,7 +76,7 @@
         <!-- test -->
         <junit.version>4.12</junit.version>
         <hamcrest.version>1.3</hamcrest.version>
-        <mockito.version>2.19.1</mockito.version>
+        <mockito.version>2.20.0</mockito.version>
         <slf4j.version>1.7.25</slf4j.version>
         <logback.version>1.2.3</logback.version>
         <maven-invoker.version>3.0.1</maven-invoker.version>