Cherry-pick to get Ruby 3.1 support in protobuf 3.20.0 (#9657)

* Allow pre-compiled binaries for ruby 3.1.0 (#9566)

* Allow pre-compiled binaries for ruby 3.1.1

* add comment

* fix build and use ruby 3.1.0

* add ruby31 to build CI for tests and release

* trying to fix ci

* install ruby 3.1.0 in ruby_build_environment.sh

* use head for rvm to install 3.1.0

* just install master version of rvm in prepare_build_macos_rc

* force install of master rvm in ruby_build_environment.sh

* Use coroutine=universal when compiling ruby31

* use ucontext

* fix filename

* fix coroutine name

* use git head for rake-compiler-dock

* use newest rake-compiler-dock version

* Updated CHANGES.txt for Ruby changes.

* Fixed Ruby 3.1 tests by marking intersect? as unimplemented. (#9645)

* Fixed Ruby 3.1 tests by marking intersect? as unimplemented.

* Updated compatibility tests.

Co-authored-by: Marco Concetto Rudilosso <marcoconcettorudilosso@gmail.com>
diff --git a/ruby/google-protobuf.gemspec b/ruby/google-protobuf.gemspec
index 4612ab7..402a6a5 100644
--- a/ruby/google-protobuf.gemspec
+++ b/ruby/google-protobuf.gemspec
@@ -17,8 +17,7 @@
   else
     s.files     += Dir.glob('ext/**/*')
     s.extensions= ["ext/google/protobuf_c/extconf.rb"]
-    s.add_development_dependency "rake-compiler-dock", "= 1.1.0"
-  end
+    s.add_development_dependency "rake-compiler-dock", "= 1.2.1"  end
   s.test_files  = ["tests/basic.rb",
                   "tests/stress.rb",
                   "tests/generated_code_test.rb"]