test(deps): update dependency junit:junit to v4 (#272)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [junit:junit](http://junit.org) ([source](https://togithub.com/junit-team/junit4)) | major | `1.0.5-SNAPSHOT` -> `4.13.1` |

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recaptcha_enterprise/pom.xml

@@ -42,8 +42,7 @@
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-recaptchaenterprise</artifactId>
     </dependency>
-    <!-- [END recaptchaenterprise_install_with_bom] -->
-
+    <!-- [START_EXCLUDE] -->
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
@@ -56,5 +55,7 @@
       <version>1.1</version>
       <scope>test</scope>
     </dependency>
+    <!-- [END_EXCLUDE] -->
   </dependencies>
+  <!-- [END recaptchaenterprise_install_with_bom] -->
 </project>