converters/simdutf: update to 6.2.0

Changelog: https://github.com/simdutf/simdutf/releases/tag/v6.1.0
Changelog: https://github.com/simdutf/simdutf/releases/tag/v6.1.1
Changelog: https://github.com/simdutf/simdutf/releases/tag/v6.1.2
Changelog: https://github.com/simdutf/simdutf/releases/tag/v6.2.0

MFH: no (soname change)