Syntax in Rack slide 3 does not work in recent version of Rack and ruby

[yaroslavrick]

Syntax in Rack slide 3 does not work in recent version of Rack (rack-3.1.16) and ruby (3.4.1):

Current line of code that does not works in slides/rack.markdown:

class Racker
  def call(env)
    [200, { 'Content-Type' => 'text/plain' }, ['Something happens!']]
  end
end

Should be fixed to this:

class Racker
  def call(env)
    [200, { 'content-type' => 'text/plain' }, ['Something happens!']]
  end
end