Raise minimum Ruby version to 3.3.0

[silug]

Short description

• Raise the minimum Ruby version to 3.3.0 in openvox.gemspec
• Set TargetRubyVersion to 3.3 in .rubocop.yml
• Fix rubocop warnings
• Remove Ruby 3.2 and JRuby 9 from the test matrix
• Add JRuby 10.0.5 and 10.1 to the test matrix

Checklist

I have:

• read the CONTRIBUTING.md document
• read and accepted the Developer Certificate of Origin document and added a Signed-off-by annotation to each of my commits
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)