Merge branch 'release/2.1' into 'release/3.1'

src/Servers/Kestrel/test/InMemory.FunctionalTests/UpgradeTests.cs

-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;