Relax *.ani file length requirement in RIFF header

Many *.ani files online have incorrect length in the RIFF header, see #5, #6

Author: quantum5

win2xcur/parser/ani.py

@@ -32,7 +32,7 @@ def can_parse(cls, blob: bytes) -> bool:
             signature, size, subtype = cls.RIFF_HEADER.unpack(blob[:cls.RIFF_HEADER.size])
         except struct.error:
             return False
-        return signature == cls.SIGNATURE and size == len(blob) - 8 and subtype == cls.ANI_TYPE
+        return signature == cls.SIGNATURE and subtype == cls.ANI_TYPE
 
     def __init__(self, blob: bytes) -> None:
         super().__init__(blob)