fix python 3.11 compatibility

Author: Tuan Tran

tests/units/training/test_get_trainer.py

@@ -23,7 +23,7 @@ def __post_init__(self):
 @dataclass
 class Config:
     foobar: str = "test"
-    cfg: Foo = Foo()
+    cfg: Foo = field(default_factory=lambda: Foo())
     c: float = field(init=False)
 
     def __post_init__(self):