Fix circular require between webdrivers.rb and railtie.rb

[amatsuda]

webdrivers.rb requires webdrivers/railtie.rb,

webdrivers/lib/webdrivers.rb

Line 7 in 161d1bb

require 'webdrivers/railtie' if defined?(Rails)

and webdrivers/railtie.rb requires webdrivers.rb.

webdrivers/lib/webdrivers/railtie.rb

Line 3 in 161d1bb

require 'webdrivers'

This causes warning: loading in progress, circular require considered harmful warning from the Ruby interpreter.

Here's a minimum step to reproduce.

$ ruby -w -rrails -rwebdrivers -ep
<internal:.../rubygems/core_ext/kernel_require.rb>:148: warning: <internal:.../rubygems/core_ext/kernel_require.rb>:148: warning: loading in progress, circular require considered harmful - .../webdrivers-5.0.0/lib/webdrivers.rb
	from <internal:.../rubygems/core_ext/kernel_require.rb>:149:in  `require'
	from <internal:.../rubygems/core_ext/kernel_require.rb>:160:in  `rescue in require'
	from <internal:.../rubygems/core_ext/kernel_require.rb>:160:in  `require'
	from .../webdrivers-5.0.0/lib/webdrivers.rb:7:in  `<top (required)>'
	from <internal:.../rubygems/core_ext/kernel_require.rb>:96:in  `require'
	from <internal:.../rubygems/core_ext/kernel_require.rb>:96:in  `require'
	from .../webdrivers-5.0.0/lib/webdrivers/railtie.rb:3:in  `<top (required)>'
	from <internal:.../rubygems/core_ext/kernel_require.rb>:148:in  `require'
	from <internal:.../rubygems/core_ext/kernel_require.rb>:148:in  `require'

This patch fixes the warning by simply removing the require call in webdrivers/railtie.rb, since there won't be any actual use case where directly requiring webdrivers/railtie.rb without requiring webdrivers.rb (via bundler in most cases).

[kapoorlakshya]

Thanks for your contribution!

P.S. Test failure is unrelated to your changes.