fix: CI checkout auth + Wrmse test failure

- Publish.yml: Change workflow permissions from {} to contents:read
  to fix GITHUB_TOKEN having no scopes for actions/checkout@v4
- Wrmse.cs: Use DateTime.UtcNow instead of DateTime.MinValue in
  Update(double,double,double) to match Beta/Covariance pattern
- Bump version to 0.8.5

lib/VERSION

@@ -1 +1 @@
-0.8.4
+0.8.5