It is already declared as:
> This behavior is slated to be removed in Ruby 4.0

https://github.com/ruby/ruby/actions/runs/5956398507/job/16157091112

This has been extremely flaky on macOS GitHub Actions.
Benoit suggested to quarantine it if it's too problematic (it is) and
there's no reasonable fix in a short time (it already took too long).
So this commit follows the suggestion.

We should remove revert this once rb_cloexec_open() is fixed.

Deprecate Kernel#open and IO support for subprocess creation and
forking. This deprecates subprocess creation and forking in

- Kernel#open
- URI.open
- IO.binread
- IO.foreach
- IO.readlines
- IO.read
- IO.write

This behavior is slated to be removed in Ruby 4.0

[Feature #19630]