build(deps): bump coverlet.msbuild from 2.8.1 to 2.9.0 (#462)

Author: dependabot-preview[bot]

test/Directory.Build.props

@@ -19,7 +19,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="coverlet.msbuild" Version="2.8.1" />
+    <PackageReference Include="coverlet.msbuild" Version="2.9.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.6.1" />
     <PackageReference Include="NSubstitute" Version="3.1.0" />
     <PackageReference Include="xunit" Version="2.4.1" />