📝 Update source examples and docs from Python 3.9 to 3.10 (#14900)

docs_src/handling_errors/tutorial002_py310.py

@@ -0,0 +1,16 @@
+from fastapi import FastAPI, HTTPException
+
+app = FastAPI()
+
+items = {"foo": "The Foo Wrestlers"}
+
+
+@app.get("/items-header/{item_id}")
+async def read_item_header(item_id: str):
+    if item_id not in items:
+        raise HTTPException(
+            status_code=404,
+            detail="Item not found",
+            headers={"X-Error": "There goes my error"},
+        )
+    return {"item": items[item_id]}