Add '"nodejs20.x"' to AwsLambdaRuntime

[cpcwood]

HI,

When using the most recent version of serverless (v3.37.0) with the recently released nodejs20.x runtime, I get the type error:

Type '"nodejs20.x"' is not assignable to type 'AwsLambdaRuntime | undefined'. Did you mean '"nodejs12.x"'?ts(2820)

Please can this package be updated to match the serverless v3.37.0 package options?

Thank you! 😄

Serverless repo ref: serverless/serverless#12251

[cpcwood]

Didn't see the active MR for this already. Closing