Reduce target frameworks for test project

Author: mnadareski

SabreTools.Hashing.Test/SabreTools.Hashing.Test.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFrameworks>net472;net48;net6.0;net7.0;net8.0;net9.0</TargetFrameworks>
+        <TargetFrameworks>net6.0;net8.0;net9.0</TargetFrameworks>
         <CheckEolTargetFramework>false</CheckEolTargetFramework>
         <IsPackable>false</IsPackable>
         <LangVersion>latest</LangVersion>