Update README.md

Author: shimat

README.md

@@ -57,7 +57,7 @@ If you do not use NuGet, get DLL files from the [release page](https://github.co
 * [OpenCV 4.10.0](http://opencv.org/) with [opencv_contrib](https://github.com/opencv/opencv_contrib)
 
 ## Requirements
-* [.NET Framework 4.8](http://www.microsoft.com/ja-jp/download/details.aspx?id=1639) / [.NET 6](https://www.microsoft.com/net/download) or later / .NET Standard 2.0
+* [.NET Framework 4.8](http://www.microsoft.com/ja-jp/download/details.aspx?id=1639) / [.NET 8](https://www.microsoft.com/net/download) or later / .NET Standard 2.0
 * (Windows) [Visual C++ 2022 Redistributable Package](https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads)
 * (Windows Server) Media Foundation
 ```