Remove redundant #include <stdint.h>

Already included transitively via QuantTypes.h, as noted by @radarhere.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Your Name

src/libImaging/QuantPngQuant.c

@@ -8,7 +8,6 @@
  *
  */
 
-#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>