chore(changelog): update CHANGELOG.md

Author: ns-vasilev

CHANGELOG.md

@@ -49,6 +49,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Remove `nonisolated(unsafe)`
   - Contributed by [@ns-vasilev](https://github.com/ns-vasilev) in Pull Request [#39](https://github.com/space-code/log/pull/39).
 
+### Testing
+- Fix updating a log level
+  - Contributed by [@ns-vasilev](https://github.com/ns-vasilev) in Pull Request [#42](https://github.com/space-code/log/pull/42).
+
 ### Uncategorized Changes
 - Add renovate.json
   - Contributed by [@renovate[bot]](https://github.com/renovate[bot]) in Pull Request [#12](https://github.com/space-code/log/pull/12).