Adds vintage agent to zipkin-tests to help avoid time lost downstream

This prevents us from interfering with JUnit 4 runtimes.

See openzipkin/zipkin-gcp#130

pom.xml

@@ -310,6 +310,12 @@
         <version>${junit.jupiter.version}</version>
       </dependency>
 
+      <dependency>
+        <groupId>org.junit.vintage</groupId>
+        <artifactId>junit-vintage-engine</artifactId>
+        <version>${junit.jupiter.version}</version>
+      </dependency>
+
       <!--
       Current versions of JUnit5 provide the above junit-jupiter artifact for convenience but we may
       still have transitive dependencies on these older artifacts and have to make sure they're all

zipkin-tests/pom.xml

@@ -45,9 +45,11 @@
       <artifactId>gson</artifactId>
     </dependency>
 
+    <!-- This prevents us from interfering with JUnit 4 runtimes.
+         See https://github.com/openzipkin/zipkin-gcp/issues/130 -->
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
+      <groupId>org.junit.vintage</groupId>
+      <artifactId>junit-vintage-engine</artifactId>
     </dependency>
     <dependency>
       <groupId>org.junit.jupiter</groupId>