SUSE-SU-2025:21220-1

This update for libpng16 fixes the following issues:

• CVE-2025-66293: Fixed out-of-bounds read in png_image_read_composite (bsc#1254480).
• CVE-2025-64505: Fixed heap buffer over-read in png_do_quantize via malformed palette index (bsc#1254157).
• CVE-2025-64506: Fixed heap buffer over-read in png_write_image_8bit with 8-bit input and convert_to_8bit enabled (bsc#1254158).
• CVE-2025-64720: Fixed buffer overflow in png_image_read_composite via incorrect palette premultiplication (bsc#1254159).
• CVE-2025-65018: Fixed heap buffer overflow in png_combine_row triggered via png_image_finish_read (bsc#1254160).