Update Kotlin Version to 1.6.20

[TheUltDev]

Fixes React Native 0.72

[AlkanV]

this is need for apps that using gradle version 7.3 or above. including me i believe there are multiple projects awaiting this PR to be merged. for example, i did manual modifications on node_modules to make it work. Can we merge this PR as soon as possible?
Thanks

[AlkanV]

@reime005 hey, could you please take a look at this PR?

thanks

[JonathanColetti]

The error for this incase anyone was wondering is The Android Gradle plugin supports only kotlin-android-extensions Gradle plugin version 1.6.20 and higher

[cchampou]

@TheUltDev I'll be using your branch in my project, since I have the same issue and this may work pretty well.

[TheUltDev]

Closing this since it's a duplicate of #320 which is a more permanent solution.

[dusanristic]

I believe this is not a duplication of #320. If you check what has changed, it's only the way we set the Kotlin version, whereas this issue is focused on upgrading Kotlin to 1.6.20. Merging #320 will not solve the problem we are currently facing; in other words, it will not update the Kotlin version.

[Hasham24]

Still encountering this problem with React Native version 0.72.8, and the error persists as follows: