[algorithms][api] Fix initialization of binary variable content

beat/web/algorithms/api.py

@@ -182,7 +182,7 @@ def binary(request, author_name, object_name, version=None):
 
         file = request.FILES['binary']
 
-        binary_data = ''
+        binary_data = b''
         for chunk in file.chunks():
             binary_data += chunk