write_png fix!

Author: andrewgiessel

folium/utilities.py

@@ -324,8 +324,9 @@ def write_png(array):
             frame = array_full[:,:,component]
             array_full[:,:,component] = (frame / frame.max() * 255)
         array_full = array_full.astype('uint8')
-    width, height = array_full.shape[:2]
-
+    height, width = array_full.shape[:2]
+    array_full = np.flipud(array_full)
+    
     array_full = array_full.tobytes()
 
     # reverse the vertical line order and add null bytes at the start