restore DEFAULT_DTYPE

Author: rabernat

src/zarr/core/metadata/v3.py

@@ -618,8 +618,7 @@ def from_numpy(cls, dtype: np.dtype[Any]) -> DataType:
     @classmethod
     def parse(cls, dtype: None | DataType | Any) -> DataType:
         if dtype is None:
-            # the default dtype
-            return DataType.float64
+            return DataType[DEFAULT_DTYPE]
         if isinstance(dtype, DataType):
             return dtype
         try: