Update tasks endpoint to use pymatgen models

src/mp_api/tasks/client.pyi

@@ -0,0 +1,9 @@
+from typing import List, Optional
+from mp_api.tasks.models import TaskDoc
+
+
+class TaskRester:
+    def query_by_task_id(
+        self, task_id, fields: Optional[List[str]] = None, monty_decode: bool = True
+    ) -> TaskDoc:
+        ...

src/mp_api/tasks/models.py

@@ -3,9 +3,10 @@
 from typing import List
 
 from monty.json import MontyDecoder
-from mp_api.materials.models import Structure, Composition
 from pydantic import BaseModel, Field, validator
 
+from pymatgen.core.structure import Structure
+from pymatgen.core.composition import Composition
 from pymatgen.core.periodic_table import Element
 
 monty_decoder = MontyDecoder()