Upgrade json gem to 2.7.2

What does this MR do and why?

This MR upgrades the json gem from 2.6.3 to 2.7.2 (the same version in use by the GDK since July 1st). The reason I opened this MR is that I started seeing the following error when running gdk update:

/Users/pedropombeiro/.local/share/mise/installs/ruby/3.2.3/lib/ruby/gems/3.2.0/gems/bundler-2.5.11/lib/bundler/runtime.rb:304:in `check_for_activated_spec!': You have already activated json 2.7.2, but your Gemfile requires json 2.6.3. Prepending bundle exec to your command may solve this. (Gem::LoadError)

I see that in $GDK_ROOT/gitlab we're using 2.6.3:

$ bundle show json
/Users/pedropombeiro/.local/share/mise/installs/ruby/3.2.3/lib/ruby/gems/3.2.0/gems/json-2.6.3

but on $GDK_ROOT we're using 2.7.2:

bundle show json
/Users/pedropombeiro/.local/share/mise/installs/ruby/3.2.3/lib/ruby/gems/3.2.0/gems/json-2.7.2

The upgrade to json 2.7.2 in the GDK came with gitlab-styles 12.0.0:

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