changes to default web server broke my build

[aliuk2012]

Hi,

A repo I'm working on was working perfectly until the recent update from grape-swagger 1.4.2 to 1.5 where I started getting rackup errors .

.asdf/installs/ruby/3.1.2/lib/ruby/gems/3.1.0/gems/bundler-2.3.20/lib/bundler/rubygems_integration.rb:308:in `block in replace_bin_path': can't find executable rackup for gem rack (Gem::Exception)

I managed to track it down to this change #853, my repo already has puma gem installed and configured but now with this change I have to pass in extra params to rackup to define which server to use rackup --server puma.

It might be worth documenting this change a bit more in the update path doc.
Is there a better way to allow developers to perhaps exclude Webrick when setting up grape-swagger?