[fix] arxiv engine

searx/engines/arxiv.py

@@ -29,7 +29,7 @@ def request(query, params):
     # basic search
     offset = (params['pageno'] - 1) * number_of_results
 
-    string_args = dict(query=query,
+    string_args = dict(query=query.decode('utf-8'),
                        offset=offset,
                        number_of_results=number_of_results)
 

tests/unit/engines/test_arxiv.py

@@ -8,7 +8,7 @@ from searx.testing import SearxTestCase
 class TestBaseEngine(SearxTestCase):
 
     def test_request(self):
-        query = 'test_query'
+        query = 'test_query'.encode('utf-8')
         dicto = defaultdict(dict)
         dicto['pageno'] = 1
         params = arxiv.request(query, dicto)