✨ Add docs and tests for Python 3.9 and Python 3.10 (#3712)

Co-authored-by: Thomas Grainger <tagrain@gmail.com>

docs_src/body_updates/tutorial002_py310.py

@@ -0,0 +1,35 @@
+from fastapi import FastAPI
+from fastapi.encoders import jsonable_encoder
+from pydantic import BaseModel
+
+app = FastAPI()
+
+
+class Item(BaseModel):
+    name: str | None = None
+    description: str | None = None
+    price: float | None = None
+    tax: float = 10.5
+    tags: list[str] = []
+
+
+items = {
+    "foo": {"name": "Foo", "price": 50.2},
+    "bar": {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},
+    "baz": {"name": "Baz", "description": None, "price": 50.2, "tax": 10.5, "tags": []},
+}
+
+
+@app.get("/items/{item_id}", response_model=Item)
+async def read_item(item_id: str):
+    return items[item_id]
+
+
+@app.patch("/items/{item_id}", response_model=Item)
+async def update_item(item_id: str, item: Item):
+    stored_item_data = items[item_id]
+    stored_item_model = Item(**stored_item_data)
+    update_data = item.dict(exclude_unset=True)
+    updated_item = stored_item_model.copy(update=update_data)
+    items[item_id] = jsonable_encoder(updated_item)
+    return updated_item