Ruby 3.x support

[bensandland]

I have been working on adding functionality to build the gem for the mingw-ucrt platform. In order to do that I have modified the Rakefile, made a "compile" task and modified the previously defined "build" task.

The build task will iterate through the supported platforms, build the externals (if .dll is missing) and then move the DLLs from eg 'x86Release' -> 'Release' and then the gem is built.

This results in 4 .gem files in the pkg directory, x86/x64-mingw + x86/x64-mingw-ucrt. These changes also means that the compilation and moving of files is all handled in the Rakefile, and the .gemspec only notifies for any missing DLLs. This does however mean that building the Gem is best done through the Rakefile, since running "gem build rautomation" will assume the DLLs are compiled and placed within their respective "Release" folder.

To compile and build the .gem files use rake task build or install

Regarding the change from notepad to regedit in the specs I changed this because I was no longer able to interact with notepad on Windows 11. It seems like the UWP apps are containerized in some way and automating these has to be done with a different API

Apologies for the messy commit. I ended up doing too many things at once after parking the task for a bit. Let me know if you have any questions or suggestions regarding this update.