OSV-2026-621 Use-of-uninitialized-value in vcardtime_from_string

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=505903588 Crash type: Use-of-uninitialized-value Crash state: vcardtimefromstring vcardvaluenewfromstring parsevcard...