Bump com.spotify:github-client from 0.1.59 to 0.2.15

Bumps [com.spotify:github-client](https://github.com/spotify/github-java-client) from 0.1.59 to 0.2.15.
- [Release notes](https://github.com/spotify/github-java-client/releases)
- [Commits](spotify/github-java-client@v0.1.59...v0.2.15)

---
updated-dependencies:
- dependency-name: com.spotify:github-client
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pom.xml

@@ -91,7 +91,7 @@
     <dependency>
       <groupId>com.spotify</groupId>
       <artifactId>github-client</artifactId>
-      <version>0.1.59</version>
+      <version>0.2.15</version>
     </dependency>
 
     <dependency>