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

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

docs_src/query_params/tutorial004_py310.py

@@ -0,0 +1,17 @@
+from fastapi import FastAPI
+
+app = FastAPI()
+
+
+@app.get("/users/{user_id}/items/{item_id}")
+async def read_user_item(
+    user_id: int, item_id: str, q: str | None = None, short: bool = False
+):
+    item = {"item_id": item_id, "owner_id": user_id}
+    if q:
+        item.update({"q": q})
+    if not short:
+        item.update(
+            {"description": "This is an amazing item that has a long description"}
+        )
+    return item