fixup: remove remove unused alias in code

doc/en/example/assertion/failure_demo.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import pytest
 from pytest import raises
 

doc/en/example/assertion/global_testmodule_config/conftest.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import os.path
 
 import pytest

doc/en/example/assertion/global_testmodule_config/test_hello_world.py

@@ -1,3 +1,6 @@
+from __future__ import annotations
+
+
 hello = "world"
 
 

doc/en/example/assertion/test_failures.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import os.path
 import shutil
 

doc/en/example/assertion/test_setup_flow_example.py

@@ -1,3 +1,6 @@
+from __future__ import annotations
+
+
 def setup_module(module):
     module.TestStateFullThing.classcount = 0