Add Ruby 3.2 Support for Rails apps using this as File.exists? was removed

[ericfirth]

Getting the following error when I try to upgrade my app to Ruby 3.2. Apparently File.exists? alias has been removed

NoMethodError: undefined method `exists?' for File:Class
/__w/truva/truva/vendor/bundle/ruby/3.2.0/gems/configatron-4.5.1/lib/configatron/integrations/rails.rb:45:in `block in init'
/__w/truva/truva/vendor/bundle/ruby/3.2.0/gems/configatron-4.5.1/lib/configatron/integrations/rails.rb:44:in `each'
/__w/truva/truva/vendor/bundle/ruby/3.2.0/gems/configatron-4.5.1/lib/configatron/integrations/rails.rb:44:in `init'
/__w/truva/truva/config/initializers/configatron.rb:6:in `<top (required)>'
/__w/truva/truva/Rakefile:7:in `require_relative'
/__w/truva/truva/Rakefile:7:in `<top (required)>'
/__w/truva/truva/vendor/bundle/ruby/3.2.0/gems/rake-13.0.6/exe/rake:27:in `<top (required)>'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/cli/exec.rb:58:in `load'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/cli/exec.rb:58:in `kernel_load'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/cli/exec.rb:[23](https://github.com/viewthespace/truva/actions/runs/7254710934/job/19764010589?pr=6395#step:14:24):in `run'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/cli.rb:492:in `exec'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/vendor/thor/lib/thor.rb:392:in `dispatch'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/cli.rb:34:in `dispatch'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/vendor/thor/lib/thor/base.rb:485:in `start'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/cli.rb:28:in `start'
/home/circleci/.rubygems/gems/bundler-2.4.12/exe/bundle:45:in `block in <top (required)>'
/home/circleci/.rubygems/gems/bundler-2.4.12/lib/bundler/friendly_errors.rb:117:in `with_friendly_errors'
/home/circleci/.rubygems/gems/bundler-2.4.12/exe/bundle:33:in `<top (required)>'
/home/circleci/.rubygems/bin/bundle:[25](https://github.com/viewthespace/truva/actions/runs/7254710934/job/19764010589?pr=6395#step:14:26):in `load'
/home/circleci/.rubygems/bin/bundle:25:in `<main>'

https://bugs.ruby-lang.org/issues/17391

Added a PR for this: #112