Support for Microsoft.Extensions.DependencyInjection 6.0.0

[danielmarbach]

Originally reported by @SimonCropp

This brings in support for Microsoft.Extensions.DependencyInjection 6.0.0. ServiceCollection has been moved into the abstractions at some point. When trying to use NServiceBus.Extensions.DependencyInjection with Microsoft.Extensions.DependencyInjection 6.0.0

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <OutputType>Exe</OutputType>
    <LangVersion>7.3</LangVersion>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="NServiceBus" Version="7.8.0" />
    <PackageReference Include="NServiceBus.Extensions.DependencyInjection" Version="1.0.1" />
    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
  </ItemGroup>
</Project>

the following error occurs

  Program.cs(4, 20): [CS0433] The type 'ServiceCollection' exists in both 'Microsoft.Extensions.DependencyInjection.Abstractions, Version=6.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60' and 'Microsoft.Extensions.DependencyInjection, Version=2.1.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'