Remove unused imports

Author: Vasileios Karakasis

unittests/test_autodetect.py

@@ -6,7 +6,6 @@
 import json
 import os
 import pytest
-import shutil
 
 
 from reframe.core.runtime import runtime

unittests/test_cli.py

@@ -10,7 +10,6 @@
 import os
 import pytest
 import re
-import shutil
 import sys
 
 import reframe.core.environments as env