Fix pixels reverse solution to use width for swapRows

The proposed solution for reversePic erroneously passes the height of the
image to the ancillary function that swaps rows. Updated to use width
instead.

Signed-off-by: Cosmin Popa <[email protected]>

laborator/content/operatii-memorie-gdb/solution/3-pixels/pixels.c

@@ -34,7 +34,7 @@ void reversePic(Picture *pic)
 {
 	for (int i = 0; i < pic->height / 2; ++i)
 		swapRows(pic->pix_array[i], pic->pix_array[pic->height - 1 - i],
-				pic->height);
+				pic->width);
 }
 
 int main(void)