refactor: remove unused imports

gns3server/utils/asyncio/input_stream.py

@@ -6,7 +6,6 @@ Parser for VT100 input stream.
 
 import re
 
-import six
 from prompt_toolkit.key_binding.input_processor import KeyPress
 from prompt_toolkit.keys import Keys
 

gns3server/utils/asyncio/pool.py

@@ -16,7 +16,6 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import asyncio
-import sys
 
 
 class Pool:

gns3server/utils/asyncio/raw_command_server.py

@@ -16,9 +16,7 @@
 
 import asyncio
 import asyncio.subprocess
-import copy
 import logging
-import re
 
 log = logging.getLogger(__name__)