Grape 2.0.2 compatibility

Running on grape 2.0.2 resulted in the following exceptions:

    NameError:
      uninitialized constant Grape::ContentTypes::CONTENT_TYPES
    # ./lib/grape-swagger/endpoint.rb:15:in `content_types_for'

    NoMethodError:
      undefined method `formatters' for module Grape::Formatter
    # ./lib/grape-swagger/endpoint.rb:14:in `content_types_for'

This is due to internal refactorings in grape as of v2.0.2, specifically
ruby-grape/grape@fb67ea99

Fixes ruby-grape#939

Author: padde

grape-swagger.gemspec

@@ -15,7 +15,7 @@ Gem::Specification.new do |s|
   s.metadata['rubygems_mfa_required'] = 'true'
 
   s.required_ruby_version = '>= 3.0'
-  s.add_runtime_dependency 'grape', '>= 1.7', '< 3.0'
+  s.add_runtime_dependency 'grape', '>= 2.2.0', '< 3.0'
   s.add_runtime_dependency 'rack-test', '~> 2'
 
   s.files = Dir['lib/**/*', '*.md', 'LICENSE.txt', 'grape-swagger.gemspec']

lib/grape-swagger/doc_methods/produces_consumes.rb

@@ -7,7 +7,7 @@ class << self
         def call(*args)
           return ['application/json'] unless args.flatten.present?
 
-          args.flatten.map { |x| Grape::ContentTypes::CONTENT_TYPES[x] || x }.uniq
+          args.flatten.map { |x| Grape::ContentTypes::DEFAULTS[x] || x }.uniq
         end
       end
     end

lib/grape-swagger/endpoint.rb

@@ -11,8 +11,8 @@ def content_types_for(target_class)
 
       if content_types.empty?
         formats       = [target_class.format, target_class.default_format].compact.uniq
-        formats       = Grape::Formatter.formatters(**{}).keys if formats.empty?
-        content_types = Grape::ContentTypes::CONTENT_TYPES.select do |content_type, _mime_type|
+        formats       = Grape::Formatter::DEFAULTS.keys if formats.empty?
+        content_types = Grape::ContentTypes::DEFAULTS.select do |content_type, _mime_type|
           formats.include? content_type
         end.values
       end