Remove code examples for Python 3.8 in `advanced_middleware`

docs/en/docs/advanced/middleware.md

@@ -57,13 +57,13 @@ Enforces that all incoming requests must either be `https` or `wss`.
 
 Any incoming request to `http` or `ws` will be redirected to the secure scheme instead.
 
-{* ../../docs_src/advanced_middleware/tutorial001.py hl[2,6] *}
+{* ../../docs_src/advanced_middleware/tutorial001_py39.py hl[2,6] *}
 
 ## `TrustedHostMiddleware` { #trustedhostmiddleware }
 
 Enforces that all incoming requests have a correctly set `Host` header, in order to guard against HTTP Host Header attacks.
 
-{* ../../docs_src/advanced_middleware/tutorial002.py hl[2,6:8] *}
+{* ../../docs_src/advanced_middleware/tutorial002_py39.py hl[2,6:8] *}
 
 The following arguments are supported:
 
@@ -78,7 +78,7 @@ Handles GZip responses for any request that includes `"gzip"` in the `Accept-Enc
 
 The middleware will handle both standard and streaming responses.
 
-{* ../../docs_src/advanced_middleware/tutorial003.py hl[2,6] *}
+{* ../../docs_src/advanced_middleware/tutorial003_py39.py hl[2,6] *}
 
 The following arguments are supported:
 

tests/test_tutorial/test_advanced_middleware/test_tutorial001.py

@@ -1,6 +1,6 @@
 from fastapi.testclient import TestClient
 
-from docs_src.advanced_middleware.tutorial001 import app
+from docs_src.advanced_middleware.tutorial001_py39 import app
 
 
 def test_middleware():

tests/test_tutorial/test_advanced_middleware/test_tutorial002.py

@@ -1,6 +1,6 @@
 from fastapi.testclient import TestClient
 
-from docs_src.advanced_middleware.tutorial002 import app
+from docs_src.advanced_middleware.tutorial002_py39 import app
 
 
 def test_middleware():

tests/test_tutorial/test_advanced_middleware/test_tutorial003.py

@@ -1,7 +1,7 @@
 from fastapi.responses import PlainTextResponse
 from fastapi.testclient import TestClient
 
-from docs_src.advanced_middleware.tutorial003 import app
+from docs_src.advanced_middleware.tutorial003_py39 import app
 
 
 @app.get("/large")