Remove obsolete checkpointing API warning

libmuscle/python/libmuscle/instance.py

@@ -6,7 +6,6 @@
 from typing import cast, Dict, List, Optional, Tuple, overload
 # TODO: import from typing module when dropping support for python 3.7
 from typing_extensions import Literal
-import warnings
 
 from ymmsl import (Identifier, Operator, SettingValue, Port, Reference,
                    Settings)
@@ -116,11 +115,6 @@ def __init__(
         self.__is_shut_down = False
 
         self._flags = InstanceFlags(flags)
-        if InstanceFlags.USES_CHECKPOINT_API in self._flags:
-            warnings.warn(
-                    'Checkpointing in MUSCLE3 version 0.6.0 is still in'
-                    ' development: the API may change in a future MUSCLE3'
-                    ' release.')
 
         # Note that these are accessed by Muscle3, but otherwise private.
         self._name, self._index = self.__make_full_name()