pythongh-109295: Fix test_os.test_access_denied() for TEMP=cwd (python#109299)

Fix test_os.test_access_denied() when the TEMP environment variable
is equal to the current working directory. Run the test using a
different filename, since self.fname already exists in this case.

Author: vstinner

Lib/test/test_os.py

@@ -737,7 +737,7 @@ def test_access_denied(self):
         # denied. See issue 28075.
         # os.environ['TEMP'] should be located on a volume that
         # supports file ACLs.
-        fname = os.path.join(os.environ['TEMP'], self.fname)
+        fname = os.path.join(os.environ['TEMP'], self.fname + "_access")
         self.addCleanup(os_helper.unlink, fname)
         create_file(fname, b'ABC')
         # Deny the right to [S]YNCHRONIZE on the file to