jadepy: return empty bytes if asked to read 0 bytes

The CBOR parser appears to ask for 0 bytes when parsing on occasion.

Author: jgriffiths

jadepy/jade.py

@@ -2313,7 +2313,7 @@ def read(self, n):
             The bytes received
         """
         # logger.debug(f'Reading {n} bytes...')
-        bytes_ = self.impl.read(n)
+        bytes_ = self.impl.read(n) if n else bytes()
         # logger.debug(f'Received: {len(bytes_)} bytes')
         return bytes_