chore(deps): bump retrofitVersion from 2.9.0 to 2.11.0

Bumps `retrofitVersion` from 2.9.0 to 2.11.0.

Updates `com.squareup.retrofit2:retrofit` from 2.9.0 to 2.11.0
- [Release notes](https://github.com/square/retrofit/releases)
- [Changelog](https://github.com/square/retrofit/blob/trunk/CHANGELOG.md)
- [Commits](square/retrofit@2.9.0...2.11.0)

Updates `com.squareup.retrofit2:converter-gson` from 2.9.0 to 2.11.0
- [Release notes](https://github.com/square/retrofit/releases)
- [Changelog](https://github.com/square/retrofit/blob/trunk/CHANGELOG.md)
- [Commits](square/retrofit@2.9.0...2.11.0)

---
updated-dependencies:
- dependency-name: com.squareup.retrofit2:retrofit
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: com.squareup.retrofit2:converter-gson
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

api-client/build.gradle

@@ -21,7 +21,7 @@ dependencies {
   // TODO: pin okhttp to a stable version. 5.x is needed for this fix:
   //  https://github.com/square/okhttp/issues/6258
   def okhttpVersion = '5.0.0-alpha.12'
-  def retrofitVersion = '2.9.0'
+  def retrofitVersion = '2.11.0'
 
   api "com.squareup.okhttp3:okhttp:$okhttpVersion"
   api "com.squareup.retrofit2:retrofit:$retrofitVersion"