deps: update dependency org.easymock:easymock to v4 (#39)

Author: renovate-bot

pom.xml

@@ -70,7 +70,7 @@
     <grpc.version>1.27.1</grpc.version>
     <protobuf.version>3.11.4</protobuf.version>
     <junit.version>4.13</junit.version>
-    <easymock.version>3.6</easymock.version>
+    <easymock.version>4.2</easymock.version>
     <guava.version>28.2-android</guava.version>
     <threeten.version>1.4.1</threeten.version>
     <javax.annotations.version>1.3.2</javax.annotations.version>