Upgrade retrofit to 2.10.0

[alishari]

What I have done and why

• Upgrade retrofit to 2.10.0,
• Use retrofit kotlin serialization converter instead of deprecated repo.

How I'm testing it

Do tests pass?

• [ ] Run local tests on DemoDebug variant: ./gradlew testDemoDebug
• [x] Check formatting: ./gradlew --init-script gradle/init.gradle.kts spotlessApply

Is this your first pull request?

• [x] Sign the CLA
• [x] Run ./tools/setup.sh
• [x] Import the code formatting style as explained in the setup script.