Requires JRuby >= 9.4 due to needing Ruby 3.0+ compatibility.

• #439: Include gem_build_complete_path in jar for RubyGems 2.5+ extension support
• #440: Don't overwrite user-specified webserver.properties file
• #513, #521: Fix issues with openstruct used for config.webxml values on JRuby 9.3+
• #527: Fix war file path as argument for Jetty runner on Jetty 9.4.32+
• #538: Put public folders inside public for executable war
• #552, #553: Use URI.open instead of open
• #557: Replace File.exists? with File.exist? for Ruby 3.2.0+ compatibility
• #559, #575: Fixes to update Warbler to modern libs and JRuby, removing old Bundler 1.x hacks
• #562: Fix problems with spaces in path names under windows
• #571: Use newer keyword argument rubyzip 3.0 API (drops support for JRuby 9.3)
• #575: Fix Gem path issues on JRuby 9.4.x
• #574: Bump default Jetty version for executables to 9.4.58.v20250814