Small memory leak when opening image with `nclx` color profile

[bigcat88]

Did not find the function call heif_nclx_color_profile_free in the sources, look like i missed it. :(

    im_heif = pillow_heif.open_heif("../tests/images/heif_other/cat.hif")  # from this repo
    for i in range(10000000):
        nclx = pillow_heif.private.read_color_profile(im_heif[0]._handle)

Eats 500mb of RAM at the end... ~60 bytes for each opening of image with nclx profile.

Affected Versions: This leak is present in all versions. Will add test for this...