Upgrade Kotlin version to 1.6

[mdeoliveira-hw]

Summary

Upgrade kotlin version to mismatch version when build on RN > 0.69. It fixes the error of issue #309

Compatibility

OS	Implemented
iOS	✅
Android	✅

Checklist

• I have tested this on a device and a simulator
• I added the documentation in README.md
• I updated the typed files (TS and Flow)
• I've added Detox End-to-End Test(s)
• I've created a snack to demonstrate the changes: LINK HERE

[github-actions]

🎉 This PR is included in version 6.6.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[dylan-westbury]

Hi,

It now expects version 1.6.20

* What went wrong:
The Android Gradle plugin supports only kotlin-android-extensions Gradle plugin version 1.6.20 and higher.
The following dependencies do not satisfy the required version:
project ':react-native-background-upload' -> org.jetbrains.kotlin:kotlin-gradle-plugin:1.6.0

[slatqh]

Confirm, it expecting 1.6.20

FAILURE: Build failed with an exception.

• What went wrong:
  The Android Gradle plugin supports only kotlin-android-extensions Gradle plugin version 1.6.20 and higher.
  The following dependencies do not satisfy the required version:
  project ':react-native-background-upload' -> org.jetbrains.kotlin:kotlin-gradle-plugin:1.6.0

[kiratheone]

The latest AGP version requires a higher version of kotlin-android-extensions. Alternatively, you can consider downgrading for another option.
I'm experiencing this issue too.