Add coverlet to tests

Author: jeremy-visionaid

OpenMcdf.Tests/OpenMcdf.Tests.csproj

@@ -10,6 +10,11 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.2" />
+    <PackageReference Include="coverlet.msbuild" Version="6.0.2">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
     <PackageReference Include="GitHubActionsTestLogger" Version="2.4.1">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>