Update swift-lambda.rb to a newer Swift Version

[nighthawk]

I've been trying to follow this blog post but got blocked when I realised that swift-lambda.rb is locked to Swift 5.3. It'd be great to update this to a newer version to use latest Swift functions, in particular async/await.

It'd also need similar updates to newer versions of the spm-dest files for Amazon Linux 2. It seems like the current latest versions from swift.org are 5.7.1. Not sure what to do about the patches declared in the Ruby files that point to https://helgehess.eu/patches though.

[helje5]

Hm, yes, I should somehow get the patches in a repo and refer to them via GH URLs, I think I only put them on the website because it seemed easier to deploy during development.