Ruby 3.4 update

[jbourassa]

Support Ruby 3.4:

• Update rb-sys
• Fix tests (updated error message in Ruby 3.4)
• Fix example (old magnus was incompatible with 3.4)
• Update test and release workflows to use Ruby 3.4

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TODOs:

• wait for Minimum Ruby 3.3 version must be 3.3.5 oxidize-rb/rb-sys#475

• wait for Add ruby-3.4 native gem ffi/ffi#1133 and run bundle to re-add the ffi precompiled binaries to the lockfile

• Fix Windows compilation issue, see this error

  Investigation notes:

  • Ruby 3.4 detects and uses <stdckdint.h> if it's present.
  • The version of llvm rb-sys uses doesn't have stdckint (it was introduced in v18.1.6).
  • looks like the compiler thinks <stdckdint.h> is available, but then later fails to see it.

  Should be fixed once Stop pinning clang in windows ucrt oxidize-rb/actions#47 merges.

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I won't cut a new version right away given we're due for a Wasmtime version bump, so we'll create a new release soon for that.