Add Ruby 4.0 support

Author: bastelfreak

.github/workflows/unit_tests.yaml

@@ -28,6 +28,7 @@ jobs:
           - '3.2'
           - '3.3'
           - '3.4'
+          - '4.0'
           - 'jruby-9.4.8.0'
     runs-on: ubuntu-24.04
     steps:

openfact.gemspec

@@ -24,7 +24,7 @@ Gem::Specification.new do |spec|
   base = "#{__dir__}#{File::SEPARATOR}"
   spec.files = dirs.map { |path| path.sub(base, '') }
 
-  spec.required_ruby_version = '>= 2.5', '< 4.0'
+  spec.required_ruby_version = '>= 2.5', '< 5.0'
   spec.bindir = 'bin'
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']