get rid of a needless step in HashWithIndifferentAccess

There was an extra operation in
`Grape::Extensions::ActiveSupport::HashWithIndifferentAccess::ParamBuilder`
it is unnecessary, people already use Rails 4, 5 or 6. Devs who are on Rails 3
less likely will upgrade to latest Grape.

After removing that operation Grape consumes less memory.

Before: 36080 bytes
After:  32472 bytes

CHANGELOG.md

@@ -3,6 +3,7 @@
 #### Features
 
 * Your contribution here.
+* [#1940](https://github.com/ruby-grape/grape/pull/1940): Get rid of a needless step in HashWithIndifferentAccess - [@dnesteryuk](https://github.com/dnesteryuk).
 * [#1938](https://github.com/ruby-grape/grape/pull/1938): Add project metadata to the gemspec - [@orien](https://github.com/orien).
 * [#1920](https://github.com/ruby-grape/grape/pull/1920): Replace Virtus with dry-types - [@dnesteryuk](https://github.com/dnesteryuk).
 

lib/grape/dsl/inside_route.rb

@@ -84,7 +84,8 @@ def should_be_empty_array?(declared_param, passed_children_params)
         end
 
         def declared_param_is_array?(declared_param)
-          route_options_params[declared_param.to_s] && route_options_params[declared_param.to_s][:type] == 'Array'
+          key = declared_param.to_s
+          route_options_params[key] && route_options_params[key][:type] == 'Array'
         end
 
         def route_options_params

lib/grape/endpoint.rb

@@ -154,7 +154,7 @@ def mount_in(router)
             methods << Grape::Http::Headers::HEAD
           end
           methods.each do |method|
-            unless route.request_method.to_s.upcase == method
+            unless route.request_method == method
               route = Grape::Router::Route.new(method, route.origin, route.attributes.to_h)
             end
             router.append(route.apply(self))

lib/grape/extensions/active_support/hash_with_indifferent_access.rb

@@ -14,10 +14,9 @@ def params_builder
           end
 
           def build_params
-            params = ::ActiveSupport::HashWithIndifferentAccess[rack_params]
+            params = ::ActiveSupport::HashWithIndifferentAccess.new(rack_params)
             params.deep_merge!(grape_routing_args) if env[Grape::Env::GRAPE_ROUTING_ARGS]
-            # TODO: remove, in Rails 4 or later ::ActiveSupport::HashWithIndifferentAccess converts nested Hashes into indifferent access ones
-            DeepHashWithIndifferentAccess.deep_hash_with_indifferent_access(params)
+            params
           end
         end
       end

lib/grape/router/route.rb

@@ -62,10 +62,12 @@ def route_path
       end
 
       def initialize(method, pattern, **options)
+        upcased_method = method.to_s.upcase
+
         @suffix     = options[:suffix]
-        @options    = options.merge(method: method.to_s.upcase)
+        @options    = options.merge(method: upcased_method)
         @pattern    = Pattern.new(pattern, **options)
-        @translator = AttributeTranslator.new(**options, request_method: method.to_s.upcase)
+        @translator = AttributeTranslator.new(**options, request_method: upcased_method)
       end
 
       def exec(env)