Add aarch64-linux-musl binary gem to CD pipeline (#168)

* Add aarch64-linux-musl binary gem to CD pipeline

Removes aarch64-linux-musl from the platform exclusion list. The comment
said the Rust target was unavailable in rake-compiler-dock, but the platform
is now fully supported by both rake-compiler-dock and the rb-sys ecosystem
used by oxidize-rb/actions/cross-gem@v1.

Fixes #167.

* Also add x64-mingw-ucrt binary gem to CD pipeline

x64-mingw-ucrt maps to the Rust target x86_64-pc-windows-gnu in the rb-sys
matrix, so the "Rust target not available in rake-compiler-dock" comment was
outdated for this platform too. x64-mingw32 remains excluded since it has
been superseded by x64-mingw-ucrt for Ruby 3.1+ and this gem targets 3.2+.

Author: dduugg

.github/workflows/cd.yml

@@ -22,11 +22,9 @@
               # Excluding:
               # `arm-linux`: Cranelift doesn't support 32-bit architectures
               # `x64-mingw32`: `x64-mingw-ucrt` should be used for Ruby 3.1+ (https://github.com/rake-compiler/rake-compiler-dock?tab=readme-ov-file#windows)
-              # `x64-mingw-ucrt`: Rust target not available in rake-compiler-dock
-              # `aarch64-linux-musl`: Rust target not available in rake-compiler-dock
               # 3.0 is deprecated as stable ruby version according to:
               #  https://github.com/oxidize-rb/actions/blob/main/fetch-ci-data/evaluate.rb#L54
-              exclude: [arm-linux, x64-mingw32, x64-mingw-ucrt, aarch64-linux-musl]
+              exclude: [arm-linux, x64-mingw32]
             stable-ruby-versions: |
               only: ['3.2', '3.3', '3.4', '4.0']