housekeeping: Add coverlet msbuild collector

Author: glennawatson

src/Splat.DependencyInjection.SourceGenerator.Tests/Splat.DependencyInjection.SourceGenerator.Tests.csproj

@@ -11,7 +11,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.2.0" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5" PrivateAssets="all" />
-    <PackageReference Include="coverlet.collector" Version="3.1.2" PrivateAssets="all" />
+    <PackageReference Include="coverlet.msbuild" Version="3.1.2" />
     <PackageReference Include="Verify.SourceGenerators" Version="1.5.0" />
     <PackageReference Include="ReactiveMarbles.SourceGenerator.TestNuGetHelper" Version="1.2.1" />
     <PackageReference Include="Verify.Xunit" Version="17.1.5" />
@@ -22,4 +22,4 @@
     <ProjectReference Include="..\Splat.DependencyInjection.SourceGenerator\Splat.DependencyInjection.SourceGenerator.csproj" />
   </ItemGroup>
 
-</Project>
+</Project>