MSVC signed/unsigned conflict between state_t.max_depth and state_t.depth

[niwred]

changing max_depth to int instead of unsigned int fixes the warning, nothing serious but might change for clean compile in the future.

typedef struct
{
    const char* regex;
    const char* input;
    subreg_capture_t* captures;
    unsigned int max_captures;
    /*unsigned*/ int max_depth;
    unsigned int capture_index;
    int depth;
    
} state_t;

[mattbucknall]

Change applied - Thanks.