fix: bump macos-example to react-native-macos 0.81.8 for the Xcode 26 fmt build error (#9843)

## Summary

`example-macos-build-check` fails on 4.3-stable: Xcode 26 (Apple clang
21) rejects fmt 11.0.2's `consteval` path (fmtlib/fmt#4740), and
react-native-macos <= 0.81.7 pins fmt 11.0.2.

This PR bumps macos example app deps to make it work.

See one of the previous failures:
https://github.com/software-mansion/react-native-reanimated/actions/runs/28580714050/job/84740022363?pr=9825

Author: MatiPl01