fix Cargo toml

Author: weikengchen

Cargo.toml

@@ -59,7 +59,7 @@ incremental = true
 debug = true
 
 [features]
-default = [ "std", "parallel" ]
-std = [ "ark-ff/std", "ark-ec/std", "ark-poly/std", "ark-std/std", "ark-serialize/std" ]
+default = ["std", "parallel"]
+std = [ "ark-ff/std", "ark-ec/std", "ark-poly/std", "ark-std/std", "ark-relations/std", "ark-serialize/std" ]
 print-trace = [ "bench-utils/print-trace" ]
 parallel = [ "std", "ark-ff/parallel", "ark-ec/parallel", "ark-poly/parallel", "ark-std/parallel", "rayon" ]