Remove excess assertions

Asserting on trying to deserialize None, or an invalid serialized
buffer result in different exceptions being raised in python2/3.
diff --git a/lib/py/test/thrift_TSerializer.py b/lib/py/test/thrift_TSerializer.py
index b941654..0a66b92 100644
--- a/lib/py/test/thrift_TSerializer.py
+++ b/lib/py/test/thrift_TSerializer.py
@@ -53,10 +53,7 @@
             42, deserialize(Message(), serialized, factory).num
         )
 
-        self.assertRaises(EOFError, deserialize, Message(), None, factory)
         self.assertRaises(EOFError, deserialize, Message(), b'', factory)
-        self.assertRaises(TypeError, deserialize, Message(), "test",  factory)
-
 
     def test_TBinaryProtocol(self):
         buf = TTransport.TMemoryBuffer()
@@ -64,7 +61,6 @@
         factory = TBinaryProtocolFactory(transport)
         self.verify(self.binary_serialized, factory)
 
-
     def test_TBinaryProtocolAccelerated(self):
         buf = TTransport.TMemoryBuffer()
         transport = TTransport.TBufferedTransportFactory().getTransport(buf)