Update TFM badges

Author: mganss

README.md

@@ -6,10 +6,8 @@ HtmlSanitizer
 [![codecov.io](https://codecov.io/github/mganss/HtmlSanitizer/coverage.svg?branch=master)](https://codecov.io/github/mganss/HtmlSanitizer?branch=master)
 [![Sonarcloud Quality Gate](https://sonarcloud.io/api/project_badges/measure?project=mganss_HtmlSanitizer&metric=alert_status)](https://sonarcloud.io/dashboard?id=mganss_HtmlSanitizer)
 
-[![netstandard1.3](https://img.shields.io/badge/netstandard-1.3-brightgreen.svg)](https://img.shields.io/badge/netstandard-1.3-brightgreen.svg)
 [![netstandard2.0](https://img.shields.io/badge/netstandard-2.0-brightgreen.svg)](https://img.shields.io/badge/netstandard-2.0-brightgreen.svg)
-[![net40](https://img.shields.io/badge/net-40-brightgreen.svg)](https://img.shields.io/badge/net-40-brightgreen.svg)
-[![net45](https://img.shields.io/badge/net-45-brightgreen.svg)](https://img.shields.io/badge/net-45-brightgreen.svg)
+[![net46](https://img.shields.io/badge/net-46-brightgreen.svg)](https://img.shields.io/badge/net-46-brightgreen.svg)
 
 HtmlSanitizer is a .NET library for cleaning HTML fragments and documents from constructs that can lead to [XSS attacks](https://en.wikipedia.org/wiki/Cross-site_scripting).
 It uses [AngleSharp](https://github.com/AngleSharp/AngleSharp) to parse, manipulate, and render HTML and CSS.