fix: compile error of zookeeper 3.4.10 on gcc9

[neverchanje]

compilation error

src/zookeeper.c: In function 'format_endpoint_info':
src/zookeeper.c:3469:21: error: '%d' directive writing between 1 and 5 bytes into a region of size between 0 and 127 [-Werror=format-overflow=]
 3469 |     sprintf(buf,"%s:%d",addrstr,ntohs(port));
      |                     ^~
src/zookeeper.c:3469:17: note: directive argument in the range [0, 65535]
 3469 |     sprintf(buf,"%s:%d",addrstr,ntohs(port));
      |                 ^~~~~~~
In file included from /usr/include/stdio.h:867,
                 from ./include/zookeeper.h:29,
                 from src/zookeeper.c:27:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:36:10: note: '__builtin___sprintf_chk' output between 3 and 134 bytes into a destination of size 128
   36 |   return __builtin___sprintf_chk (__s, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   37 |       __bos (__s), __fmt, __va_arg_pack ());
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

GCC9 generates errors on the zookeeper c client 3.4.10. My previous attempt on this issue: #667