v1.2.0

• Fix global Proc method leak by removing Proc.send :include and using direct method calls within refinements
• Add GitHub Actions CI (ruby head, 4.0.2, 3.4, truffleruby, jruby)
• Add rake and minitest as development dependencies for Ruby 4.0 compatibility
• Use $stderr instead of STDERR
• Fix typo in gemspec description ("lamdba" -> "lambda")
• Use HTTPS for homepage URL
• Remove deprecated test_files= from gemspec