gfm: fix truncation error

tilp_and_gfm/gfm/trunk/src/labels.c: In function ‘format_path’:
tilp_and_gfm/gfm/trunk/src/labels.c:91:37: error: ‘%6i’ directive output may be truncated writing between 6 and 10 bytes into a region of size 6 [-Werror=format-truncation=]
   91 |                 snprintf(str, 8, " (%6i)", n);
      |                                     ^~~

gfm/trunk/src/labels.c

@@ -88,7 +88,7 @@ static char* format_path(char *src, char *dst)
 		strcat(dst, "...");
 		strcat(dst, p);
 
-		snprintf(str, 8, " (%i)", n);
+		snprintf(str, 8, " (%i)", n%6);
 		strcat(dst, str);
 
 		free(left);