Don't require pry by default

[cmrd-senya]

There is an AUR package for Arch Linux for devdocs here: https://aur.archlinux.org/packages/devdocs-git/

Currently it doesn't start because of the error with pry:

 bundler: failed to load command: rackup (/opt/devdocs-git/.bundle/ruby/2.7.0/bin/rackup)
 ArgumentError: couldn't find login name -- expanding `~'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/pry-0.12.2/lib/pry/pry_class.rb:5:in `expand_path'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/pry-0.12.2/lib/pry/pry_class.rb:5:in `<class:Pry>'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/pry-0.12.2/lib/pry/pry_class.rb:1:in `<top (required)>'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/pry-0.12.2/lib/pry.rb:119:in `require'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/pry-0.12.2/lib/pry.rb:119:in `<top (required)>'
   /usr/lib/ruby/gems/2.7.0/gems/bundler-2.1.4/lib/bundler/runtime.rb:74:in `require'
   /usr/lib/ruby/gems/2.7.0/gems/bundler-2.1.4/lib/bundler/runtime.rb:74:in `block (2 levels) in require'
   /usr/lib/ruby/gems/2.7.0/gems/bundler-2.1.4/lib/bundler/runtime.rb:69:in `each'
   /usr/lib/ruby/gems/2.7.0/gems/bundler-2.1.4/lib/bundler/runtime.rb:69:in `block in require'
   /usr/lib/ruby/gems/2.7.0/gems/bundler-2.1.4/lib/bundler/runtime.rb:58:in `each'
   /usr/lib/ruby/gems/2.7.0/gems/bundler-2.1.4/lib/bundler/runtime.rb:58:in `require'
   /usr/lib/ruby/gems/2.7.0/gems/bundler-2.1.4/lib/bundler.rb:174:in `require'
   /opt/devdocs-git/lib/docs.rb:2:in `<top (required)>'
   /opt/devdocs-git/lib/app.rb:40:in `require'
   /opt/devdocs-git/lib/app.rb:40:in `block in <class:App>'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/sinatra-2.0.7/lib/sinatra/base.rb:1426:in `configure'
   /opt/devdocs-git/lib/app.rb:14:in `<class:App>'
   /opt/devdocs-git/lib/app.rb:6:in `<top (required)>'
   /opt/devdocs-git/config.ru:5:in `require'
   /opt/devdocs-git/config.ru:5:in `block in <main>'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/builder.rb:55:in `instance_eval'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/builder.rb:55:in `initialize'
   /opt/devdocs-git/config.ru:in `new'
   /opt/devdocs-git/config.ru:in `<main>'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/builder.rb:49:in `eval'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/builder.rb:49:in `new_from_string'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/builder.rb:40:in `parse_file'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/server.rb:319:in `build_app_and_options_from_config'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/server.rb:219:in `app'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/server.rb:354:in `wrapped_app'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/server.rb:283:in `start'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/lib/rack/server.rb:148:in `start'
   /opt/devdocs-git/.bundle/ruby/2.7.0/gems/rack-2.0.7/bin/rackup:4:in `<top (required)>'
   /opt/devdocs-git/.bundle/ruby/2.7.0/bin/rackup:23:in `load'
   /opt/devdocs-git/.bundle/ruby/2.7.0/bin/rackup:23:in `<top (required)>'

It happens because HOME environment variable is not set when devdocs is run as a systemd service. And pry requires HOME env variable to be set.

At the same time, the files in the project that use pry are requiring it explicitly anyway. So there doesn't seem to be any harm in setting require to false for pry gem, but it also fixes the issue for the aformentioned package which tries to load pry with the application and fails to because pry requires HOME to be set. In fact pry is only needed for running thor tasks and not for the webapp itself.