[fix] update qwant search url

thx to @dalf for the fix (#1365)

searx/engines/qwant.py

@@ -28,7 +28,7 @@ category_to_keyword = {'general': 'web',
                        'social media': 'social'}
 
 # search-url
-url = 'https://api.qwant.com/api/search/{keyword}?count=10&offset={offset}&f=&{query}'
+url = 'https://api.qwant.com/api/search/{keyword}?count=10&offset={offset}&f=&{query}&t={keyword}&uiv=4'
 
 
 # do search-request