Update Proposals/NNNN-UTCClock.md

Co-authored-by: Tina L <49205802+itingliu@users.noreply.github.com>

Author: phausler

Proposals/NNNN-UTCClock.md

@@ -2,7 +2,7 @@
 
 * Proposal: 
 * Authors: [Philippe Hausler](https://github.com/phausler)
-* Review Manager: 
+* Review Manager: [Tina L](https://github.com/itingliu)
 * Status: Review: Jun 10...Jun 17, 2025
 * Implementation: 
 * Review: [Pitch](https://forums.swift.org/t/pitch-utcclock/78018)