Remove duplicate version info

tests/test_version.py

@@ -0,0 +1,8 @@
+import subprocess
+
+from tortoise import __version__
+
+
+def test_version():
+    r = subprocess.run(["poetry", "version", "-s"], capture_output=True)
+    r.stdout.decode() == __version__

tortoise/__init__.py

@@ -1,10 +1,12 @@
 import asyncio
 import importlib
+import importlib.metadata as importlib_metadata
 import json
 import os
 import warnings
 from copy import deepcopy
 from inspect import isclass
+from pathlib import Path
 from types import ModuleType
 from typing import Coroutine, Dict, Iterable, List, Optional, Tuple, Type, Union, cast
 
@@ -690,7 +692,7 @@ async def do_stuff():
         loop.run_until_complete(connections.close_all(discard=True))
 
 
-__version__ = "0.20.1"
+__version__ = importlib_metadata.version(Path(__file__).parent.parent.name)
 
 __all__ = [
     "Model",