don’t use z length modifier with unsigned int

GCC and Clang print warnings:

    $ clang main.c -Wall
    main.c:30:23: warning: format specifies type 'size_t' (aka 'unsigned long') but the argument has type 'unsigned int' [-Wformat]
       30 |     printf("#%zu:\n", i);
          |              ~~~      ^
          |              %u
    1 warning generated.

    $ gcc main.c -Wall
    main.c: In function ‘main’:
    main.c:30:16: warning: format ‘%zu’ expects argument of type ‘size_t’, but argument 2 has type ‘unsigned int’ [-Wformat=]
       30 |     printf("#%zu:\n", i);
          |              ~~^      ~
          |                |      |
          |                |      unsigned int
          |                long unsigned int
          |              %u

Signed-off-by: Arkadiusz Drabczyk 
---
 man/man3/regex.3 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man/man3/regex.3 b/man/man3/regex.3
index 3069489cb..a094c3b20 100644
--- a/man/man3/regex.3
+++ b/man/man3/regex.3
@@ -392,7 +392,7 @@ int main(void)
 \&
         off = pmatch[0].rm_so + (s \- str);
         len = pmatch[0].rm_eo \- pmatch[0].rm_so;
-        printf("#%zu:\[rs]n", i);
+        printf("#%u:\[rs]n", i);
         printf("offset = %jd; length = %jd\[rs]n", (intmax_t) off,
                 (intmax_t) len);
         printf("substring = \[rs]"%.*s\[rs]"\[rs]n", len, s + pmatch[0].rm_so);
-- 
2.45.2