[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/results.py

@@ -1,5 +1,4 @@
 import re
-from collections import defaultdict
 from operator import itemgetter
 from threading import RLock
 from urllib.parse import urlparse, unquote