heap-buffer-overflow in stbi convert 16 to 8

heap-buffer-overflow in stbi convert 16 to 8: a task in MiMo-V2.6-RL-oss: Agentic RL Environments (MiMo RL release). AddressSanitizer: heap-buffer-overflow in function stbiconvert 16 to 8 in file stb/stb image.h