More consistent target framework for unit tests.

Author: rstarkov

Tests/RT.CommandLine.Tests/RT.CommandLine.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
     <OutputPath>..\..\Builds\$(Configuration)-$(TargetFramework)$(RuntimeIdentifier)\</OutputPath>
     <IntermediateOutputPath>$(BaseIntermediateOutputPath)\$(Configuration)-$(TargetFramework)$(RuntimeIdentifier)\</IntermediateOutputPath>