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

.github/workflows/Publish.yml

@@ -21,7 +21,8 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
-permissions: {}
+permissions:
+  contents: read
 
 defaults:
   run: