gems: replace pry with debug.

Replace the 'pry' gem with the 'debug' gem. The debug gem is the new
standard debugger in Ruby 3.1.

Use `binding.break` instead of `binding.pry` to set breakpoints.

Install the extension below for VS Code support.

https://github.com/ruby/debug#how-to-use
https://marketplace.visualstudio.com/items?itemName=KoichiSasada.vscode-rdbg

Gemfile

@@ -49,14 +49,13 @@ gem 'puma-metrics'
 gem 'puma_worker_killer'
 gem "rack-timeout", require: "rack/timeout/base"
 gem "parallel"
-gem "pry-byebug"
-gem "pry-rails"
 gem "ffi"
 gem "rbtrace"
 gem "good_job"
 gem "crass"
 gem "public_suffix"
 gem "elastic-apm"
+gem "debug"
 
 group :development do
   gem 'rubocop', require: false