Remove code examples for Python 3.8 in `async_tests`

docs/en/docs/advanced/async-tests.md

@@ -32,11 +32,11 @@ For a simple example, let's consider a file structure similar to the one describ
 
 The file `main.py` would have:
 
-{* ../../docs_src/async_tests/main.py *}
+{* ../../docs_src/async_tests/app_a_py39/main.py *}
 
 The file `test_main.py` would have the tests for `main.py`, it could look like this now:
 
-{* ../../docs_src/async_tests/test_main.py *}
+{* ../../docs_src/async_tests/app_a_py39/test_main.py *}
 
 ## Run it { #run-it }
 
@@ -56,7 +56,7 @@ $ pytest
 
 The marker `@pytest.mark.anyio` tells pytest that this test function should be called asynchronously:
 
-{* ../../docs_src/async_tests/test_main.py hl[7] *}
+{* ../../docs_src/async_tests/app_a_py39/test_main.py hl[7] *}
 
 /// tip
 
@@ -66,7 +66,7 @@ Note that the test function is now `async def` instead of just `def` as before w
 
 Then we can create an `AsyncClient` with the app, and send async requests to it, using `await`.
 
-{* ../../docs_src/async_tests/test_main.py hl[9:12] *}
+{* ../../docs_src/async_tests/app_a_py39/test_main.py hl[9:12] *}
 
 This is the equivalent to:
 

tests/test_tutorial/test_async_tests/test_main.py → tests/test_tutorial/test_async_tests/test_main_a.py

@@ -1,6 +1,6 @@
 import pytest
 
-from docs_src.async_tests.test_main import test_root
+from docs_src.async_tests.app_a_py39.test_main import test_root
 
 
 @pytest.mark.anyio