Bump gson from 2.8.6 to 2.8.7

Bumps [gson](https://github.com/google/gson) from 2.8.6 to 2.8.7.
- [Release notes](https://github.com/google/gson/releases)
- [Changelog](https://github.com/google/gson/blob/master/CHANGELOG.md)
- [Commits](google/gson@gson-parent-2.8.6...gson-parent-2.8.7)

---
updated-dependencies:
- dependency-name: com.google.code.gson:gson
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

extractor/build.gradle

@@ -16,5 +16,5 @@ dependencies {
 
     testImplementation 'junit:junit:4.13.2'
     testImplementation "com.squareup.okhttp3:okhttp:3.12.13"
-    testImplementation 'com.google.code.gson:gson:2.8.6'
+    testImplementation 'com.google.code.gson:gson:2.8.7'
 }