Upgrade minimum .NET Framework version for xRetry.v3 to 4.7.2

Aligns with xUnit.v3 minimum. .NET standard 2.0 is still targeted, so that is unchanged.

Author: JoshKeegan

src/xRetry.v3/xRetry.v3.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net452;netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>net472;netstandard2.0</TargetFrameworks>
 
     <IsPackable>true</IsPackable>
     <NuspecProperties>version=$(Version)</NuspecProperties>

src/xRetry.v3/xRetry.v3.nuspec

@@ -25,7 +25,7 @@
   </metadata>
 
   <files>
-    <file src="bin\Release\net452\xRetry.v3.dll" target="lib\net452" />
+    <file src="bin\Release\net472\xRetry.v3.dll" target="lib\net472" />
     <file src="bin\Release\netstandard2.0\xRetry.v3.dll" target="lib\netstandard2.0" />
 
     <file src="README.md" target="docs\" />