Bump google-http-client from 1.21.0 to 1.39.1

Bumps [google-http-client](https://github.com/googleapis/google-http-java-client) from 1.21.0 to 1.39.1.
- [Release notes](https://github.com/googleapis/google-http-java-client/releases)
- [Changelog](https://github.com/googleapis/google-http-java-client/blob/master/CHANGELOG.md)
- [Commits](googleapis/google-http-java-client@1.21.0...v1.39.1)

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

pom.xml

@@ -73,7 +73,7 @@
     <google.api.version>1.25.0</google.api.version>
     <google.guava.version>30.1-jre</google.guava.version>
     <oauth2.revision>151</oauth2.revision>
-    <google.http.version>1.21.0</google.http.version>
+    <google.http.version>1.39.1</google.http.version>
     <lombok.version>1.18.8</lombok.version>
     <java.level>8</java.level>
     <findbugs.excludeFilterFile>findbugs-exclude.xml</findbugs.excludeFilterFile>