Fix 2.7 deprecation warning in middleware/stack (#2123)

Author: Legogris

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 * Your contribution here.
 * [#2115](https://github.com/ruby-grape/grape/pull/2115): Fix declared_params regression with multiple allowed types - [@stanhu](https://github.com/stanhu).
+* [#2123](https://github.com/ruby-grape/grape/pull/2123): Fix 2.7 deprecation warning in middleware/stack - [@Legogris](https://github.com/Legogris).
 
 ### 1.5.0 (2020/10/05)
 

lib/grape/middleware/stack.rb

@@ -70,9 +70,9 @@ def [](i)
         middlewares[i]
       end
 
-      def insert(index, *args, &block)
+      def insert(index, *args, **kwargs, &block)
         index = assert_index(index, :before)
-        middleware = self.class::Middleware.new(*args, &block)
+        middleware = self.class::Middleware.new(*args, **kwargs, &block)
         middlewares.insert(index, middleware)
       end
 
@@ -83,8 +83,8 @@ def insert_after(index, *args, &block)
         insert(index + 1, *args, &block)
       end
 
-      def use(*args, &block)
-        middleware = self.class::Middleware.new(*args, &block)
+      def use(*args, **kwargs, &block)
+        middleware = self.class::Middleware.new(*args, **kwargs, &block)
         middlewares.push(middleware)
       end