Update Mockito to 2.28.2.

Fixes #13.

Author: Capstan

project.gradle

@@ -37,7 +37,7 @@ dependencies {
         exclude(group: "org.beanshell", module: "bsh");
         exclude(group: "org.yaml", module: "snakeyaml");
     };
-    testCompile(group: "org.mockito", name: "mockito-core", version: "1.9.5");
+    testCompile(group: "org.mockito", name: "mockito-core", version: "2.28.2");
 }
 
 javadoc.options.links("http://docs.oracle.com/javase/6/docs/api/");

src/test/java/com/github/fge/msgsimple/provider/LoadingMessageSourceProviderTest.java

@@ -37,6 +37,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.*;
 import static org.testng.Assert.*;