Only load from cgi what is required for Ruby 3.5

[Earlopain]

In Ruby 3.5 most of the cgi gem will be removed. Only the various escape/unescape methods will be retained by default.

But: cgi/escape only exists since Ruby 2.3. So I fall back to cgi/util on earlier versions.

https://bugs.ruby-lang.org/issues/21258

[postmodern]

The linked upstream issue is still open and they appear to still be discussing what to do with cgi. Testing under ruby-3.5.0-preview1, one can still require cgi, cgi/escape, and cgi/util, and call CGI.escapeHTML. This doesn't appear to be an issue, yet. Feel free to re-open when cgi is removed from stdlib.

[postmodern]

Hmm, it looks like hsbt's PR was merged into Ruby master, so cgi will be soft-removed in 3.5.0-preview2, with a placeholder cgi.rb file left behind recommending using cgi/escape instead. At that point I'll probably use this code from the PR instead:

      begin
        require 'cgi/escape'
      rescue LoadError
        require 'cgi/util'
      end

[Earlopain]

Sure, I changed it and left a comment for which ruby version it applies