Tortoise ORM support (#59)

* add tortoise to dependencies

* add tortoise as optional dependency in pyproject.toml

* add tortoise support (tests needed)

* Add tortoise support (also defined orm_mode in pydantic model

* tests for tortoise support

* format by black

* docs for tortoise

* delete type annotations

* delete underscore

* do it in 1 line

* add 1 line before yield

* fix in docs

* fix bug and add annotation for test

* Tweak documentation and fix Tortoise error about id update

* Improve Tortoise coverage by using get instead of filter

* Fix Pipfile.lock

docs/src/db_tortoise.py

@@ -0,0 +1,16 @@
+from fastapi import FastAPI
+from fastapi_users.db.tortoise import BaseUserModel, TortoiseUserDatabase
+from tortoise import Model
+from tortoise.contrib.starlette import register_tortoise
+
+DATABASE_URL = "sqlite://./test.db"
+
+
+class UserModel(BaseUserModel, Model):
+    pass
+
+
+user_db = TortoiseUserDatabase(UserModel)
+app = FastAPI()
+
+register_tortoise(app, modules={"models": ["path_to_your_package"]})