Remove call to binary_to_existing_atom (#712)

This function is only available from OTP 23 and ginger is stuck on OTP 22

Co-authored-by: Colin de Roos <colin@driebit.nl>

modules/mod_ginger_base/support/ginger_search.erl

@@ -166,15 +166,15 @@ parse_argument({Key, <<"undefined">>}) ->
 parse_argument({hassubjects, Subjects}) ->
     lists:map(
         fun(Subject) ->
-            {hassubject, parse_predicate(Subject)}
+            {hassubject, Subject}
         end,
         Subjects
     );
 
 parse_argument({hasobjects, Objects}) ->
     lists:map(
         fun(Object) ->
-            {hasobject, parse_predicate(Object)}
+            {hasobject, Object}
         end,
         Objects
     );
@@ -309,12 +309,6 @@ parse_argument({boost_featured, true}) ->
 parse_argument(Arg) ->
     [Arg].
 
-parse_predicate(P) ->
-    case P of
-        [Node, PredName] -> [Node, erlang:binary_to_existing_atom(PredName)];
-        _ -> P
-    end.
-
 date_facet(Property) ->
     %% A facet on a date property is a min/max range.
     [