Missing check in function check_time

Describe the bug A clear and concise description of what the bug is. RFC1123 limits the year field should be a 4-digit number and the limitation is implemented in libpng. However, if it is on purpose in libspng, just ignore this issue.

static int check_time(const struct spng_time *time)
{
    if(time == NULL) return 1;
+   if(time->year > 9999) return 1;
    if(time->month == 0 || time->month > 12) return 1;
    if(time->day == 0 || time->day > 31) return 1;
    if(time->hour > 23) return 1;
    if(time->minute > 59) return 1;
    if(time->second > 60) return 1;

    return 0;
}

NOTE: Bugs that can cause a crash or memory leak should not be reported on GitHub! Send an e-mail to contact@libspng.org instead.

To Reproduce Steps to reproduce the behavior: code snippet, PNG file (if applicable), error message(s).

Expected behavior A clear and concise description of what you expected to happen.

return 1 when year > 9999

Platform (please complete the following information):

Architecture: [e.g. x86-64, ARM64]
OS: [e.g. Windows]
Version [e.g. v0.7.2]

Additional context Add any other context about the problem here.

randy408 / libspng

Missing check in function check_time #265