revert !=net5.0 condition

Author: SergeiPavlov

Orm/Xtensive.Orm/Xtensive.Orm.csproj

@@ -49,7 +49,7 @@
   <ItemGroup Condition="'$(TargetFramework)'=='net5.0'">
     <PackageReference Include="System.Configuration.ConfigurationManager" Version="5.0.0" />
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetFramework)'!='net5.0'">
+  <ItemGroup Condition="'$(TargetFramework)'=='net6.0'">
     <PackageReference Include="System.Configuration.ConfigurationManager" Version="6.0.1" />
   </ItemGroup>
   <ItemGroup Label="Packages">