libheif: update to 1.13.0.

    pay attention to the correct chroma sample positions
    heif_image now holds a list of decoding warnings
    use AOM AOM_USAGE_ALL_INTRA mode instead of AOM_USAGE_GOOD_QUALITY
    'strict' decoding mode with more checks for standard conformity of input
    support for EXIF data >64k in JPEG output
    proper library initialization and cleanup
    separate quality settings for alpha channel (AOM)
    improve color conversion speed (no lroundf)
    build and packaging fixes

(wiz)