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

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

docs_src/dependencies/tutorial005_py310.py

@@ -0,0 +1,20 @@
+from fastapi import Cookie, Depends, FastAPI
+
+app = FastAPI()
+
+
+def query_extractor(q: str | None = None):
+    return q
+
+
+def query_or_cookie_extractor(
+    q: str = Depends(query_extractor), last_query: str | None = Cookie(None)
+):
+    if not q:
+        return last_query
+    return q
+
+
+@app.get("/items/")
+async def read_query(query_or_default: str = Depends(query_or_cookie_extractor)):
+    return {"q_or_cookie": query_or_default}