(maint) Update dependency coverlet.msbuild to 6.0.4 (#132)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

src/Diagramming.Tests/Diagramming.Tests.csproj

@@ -12,7 +12,7 @@
 
     <ItemGroup>
         <PackageReference Include="Statiq.Testing" Version="1.0.0-beta.72" />
-        <PackageReference Include="coverlet.msbuild" Version="6.0.3">
+        <PackageReference Include="coverlet.msbuild" Version="6.0.4">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
             <PrivateAssets>all</PrivateAssets>
         </PackageReference>