Update src/Microsoft.OpenApi/Extensions/StringExtensions.cs

Author: darrelmiller

src/Microsoft.OpenApi/Extensions/StringExtensions.cs

@@ -1,5 +1,5 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
-// Licensed under the MIT license.
+// Licensed under the MIT license. 
 
 using System;
 using System.Linq;