Raise major version limit for msgpack (#8466)

python/ray/includes/serialization.pxi

@@ -177,7 +177,7 @@ cdef class MessagePackSerializer(object):
                 raise Exception('Unrecognized ext type id: {}'.format(code))
         try:
             gc.disable()  # Performance optimization for msgpack.
-            return msgpack.loads(s, ext_hook=_ext_hook, raw=False)
+            return msgpack.loads(s, ext_hook=_ext_hook, raw=False, strict_map_key=False)
         finally:
             gc.enable()
 

python/setup.py

@@ -194,7 +194,7 @@ requires = [
     "google",
     "grpcio",
     "jsonschema",
-    "msgpack >= 0.6.0, < 1.0.0",
+    "msgpack >= 0.6.0, < 2.0.0",
     "numpy >= 1.16",
     "protobuf >= 3.8.0",
     "py-spy >= 0.2.0",