[mod] remove unused import

use
from searx.engines.duckduckgo import _fetch_supported_languages, supported_languages_url  # NOQA
so it is possible to easily remove all unused import using autoflake:
autoflake --in-place --recursive --remove-all-unused-imports searx tests

searx/engines/digg.py

@@ -12,10 +12,8 @@
 
 import random
 import string
-from dateutil import parser
 from json import loads
 from urllib.parse import urlencode
-from lxml import html
 from datetime import datetime
 
 # engine dependent config