Bump coverlet.collector from 6.0.3 to 6.0.4

---
updated-dependencies:
- dependency-name: coverlet.collector
  dependency-version: 6.0.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

src/Avalonia.Samples/Testing/TestableApp.Headless.NUnit/TestableApp.Headless.NUnit.csproj

@@ -15,7 +15,7 @@
     <PackageReference Include="NUnit" Version="4.4.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="5.2.0" />
     <PackageReference Include="NUnit.Analyzers" Version="4.11.2" />
-    <PackageReference Include="coverlet.collector" Version="6.0.3" />
+    <PackageReference Include="coverlet.collector" Version="6.0.4" />
   </ItemGroup>
 
   <ItemGroup>