x11/pixman: update to 0.46.0

Changes: https://lists.freedesktop.org/archives/pixman/2025-April/005025.html
PR: 286587
Approved by: maintainer timeout (2 weeks or 1 week per "Opening the gates on x11@ ports" on developers@ list)
Signed-off-by: Loukas Agorgianitis <loukas@agorgianitis.com>