fix flake8 issues

- Remove some unused imports
- ignore flake8 errors E701 and E704 because they conflict with the
  latest version of `black`

.flake8

@@ -19,4 +19,4 @@ max-line-length = 119
 copyright-check = True
 select = E,F,W,C
 copyright-regexp=Copyright \(c\) Facebook, Inc. and its affiliates. All Rights Reserved
-ignore=W503,E203
+ignore=W503,E203,E701,E704

tests/instantiate/test_positional_only_arguments.py

@@ -1,8 +1,7 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
-import sys
 from typing import Any
 
-from pytest import mark, param, skip
+from pytest import mark, param
 
 from hydra.utils import instantiate
 

tests/test_config_repository.py

@@ -1,7 +1,6 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
 import copy
 import re
-import sys
 import zipfile
 from typing import Any, List
 

tools/configen/configen/utils.py

@@ -1,5 +1,4 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
-import sys
 from enum import Enum
 from typing import Any, Dict, Iterable, List, Optional, Set