test/py: don't import pexpect

The code replaced pexpect with custom code long ago. Don't import the
unused module so it doesn't need to be installed.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/test/py/conftest.py b/test/py/conftest.py
index 7b97cba..1ec096e 100644
--- a/test/py/conftest.py
+++ b/test/py/conftest.py
@@ -17,7 +17,6 @@
 import errno
 import os
 import os.path
-import pexpect
 import pytest
 from _pytest.runner import runtestprotocol
 import ConfigParser