converters/simdutf: update to 7.3.6

Changelog: https://github.com/simdutf/simdutf/releases/tag/v7.3.5
Changelog: https://github.com/simdutf/simdutf/releases/tag/v7.3.6

MFH: 2025Q3
(cherry picked from commit 53a98335f98c912a5d5baa17aab65792fd0ecb8d)