Fix release workflow for MTP test runner and container tagging

[damianh]

Summary

The release workflow has two issues after the xunit v3 / MTP migration merged in PR #10:

1. Test step fails — dotnet test against the solution discovers the Aspire test DLL which has zero tests in CI, causing MTP exit code 8. Fixed by targeting only MicroStack.Tests.csproj with --project and excluding ContainerSmokeTests via --filter-not-class.

2. Container image not tagged with release version — The publish step relied on MinVer for tagging but didn't pass explicit tags. Now passes ContainerImageTags with the workflow's version input + latest.

Reviewer focus

• Verify the --project and --filter-not-class flags match the CI workflow
• Confirm the ContainerImageTags quoting works correctly in the YAML block

Risk / impact

• Without this fix, the release workflow would fail at the test step on .NET 10 with MTP