chore: update dependency coverlet.collector to 6.0.4 (#482)

Author: renovate-bot

Google.Cloud.EntityFrameworkCore.Spanner.IntegrationTests/Google.Cloud.EntityFrameworkCore.Spanner.IntegrationTests.csproj

@@ -28,7 +28,7 @@
     <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.0.2" />
-    <PackageReference Include="coverlet.collector" Version="6.0.2" />
+    <PackageReference Include="coverlet.collector" Version="6.0.4" />
     <PackageReference Include="Xunit.SkippableFact" Version="1.5.23" />
   </ItemGroup>