Fixed typo

Author: grkek

src/grip/exceptions/bad_request.cr

@@ -2,7 +2,7 @@ module Grip
   module Exceptions
     class BadRequest < Base
       def initialize(message : String? = nil)
-        @@status_code = HTTP::Status::BAD_REQUEST
+        @status_code = HTTP::Status::BAD_REQUEST
         @message = message if message
         @message = "Please provide a proper request to the endpoint." unless message
       end