Remove unused imports in tests (GH-14518)

diff --git a/Lib/test/test_posixpath.py b/Lib/test/test_posixpath.py
index 983e2dd..4d3d897 100644
--- a/Lib/test/test_posixpath.py
+++ b/Lib/test/test_posixpath.py
@@ -1,7 +1,6 @@
 import os
 import posixpath
 import unittest
-import warnings
 from posixpath import realpath, abspath, dirname, basename
 from test import support, test_genericpath
 from test.support import FakePath
@@ -12,6 +11,7 @@
 except ImportError:
     posix = None
 
+
 # An absolute path to a temporary filename for testing. We can't rely on TESTFN
 # being an absolute path, so we need this.