mupdf: update to 1.23.4.

MuPDF 1.23.4 (2023-10-11)

    Fix bug causing a crash when cleaning up Android draw device upon destroy.
    Fix bug where bitmaps were reused after being recycled in Android.
    Add fixed padding to ink annotation to avoid unselectable bboxes for tiny strokes.
    Add API for checking if an annotation has a Rect property.
    Fix bug where cycles in structure trees caused eternal loops.
    Fix bug where colorspaces were not retained for in-linee images during filtering.
    Change default to use CropBox rather than MediaBox.

(wiz)