Fix handling LIST before anih

ani2spritesheet.py

@@ -17,10 +17,13 @@ def analyzeANIFile(filePath):
             return {"code":-1,"msg":"File is not a ANI File!"}
         logging.debug('魔数检查完成！')
         frameRate = (1/60)*1000
+        readANIH = False
         while(True):
             chunkName = f.read(4)
-            if chunkName == b'LIST':
+            if chunkName == b'LIST' and readANIH:
                 break
+            if chunkName == b'anih':
+                readANIH = True
             chunkSize = int.from_bytes(f.read(4), byteorder='little', signed=False)
             if chunkName.lower() == b'rate':
                 logging.debug('发现自定义速率！')