Ensure invariant culture when parsing IIS log timestamps

[PrzemyslawKlys]

Summary

• parse IIS log timestamps using DateTime.ParseExact and invariant culture
• add unit test verifying parsing under a non-default culture

Testing

• dotnet build
• dotnet test

---

https://chatgpt.com/codex/tasks/task_e_68a95920a7b4832ea62f7c729101529e

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.29%. Comparing base (d555097) to head (f71a21c).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #11   +/-   ##
=======================================
  Coverage   86.29%   86.29%           
=======================================
  Files           3        3           
  Lines         124      124           
  Branches       17       17           
=======================================
  Hits          107      107           
  Misses         13       13           
  Partials        4        4           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.