Change default runtime to .NET 10

[jkuek]

.NET 8 runtime is being deprecated for Lambda

The new default should be DOTNET_10

[lachriz-aws]

Thanks for opening this issue @jkuek! And yes, you're right - as per: https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html the deprecation date is Nov 10, 2026. I'll try to carve out some time in the coming week(s) to make DOTNET_10 the default and get a new release out. Thanks again!

[jkuek]

Thanks @lachriz-aws