Update to new benchmarking framework (#126)

mnt6_753/benches/mnt6_753.rs

@@ -0,0 +1,15 @@
+use ark_algebra_bench_templates::*;
+use ark_mnt6_753::{
+    fq::Fq, fq3::Fq3, fr::Fr, Fq6, G1Projective as G1, G2Projective as G2, MNT6_753,
+};
+
+bench!(
+    Name = "MNT6_753",
+    Pairing = MNT6_753,
+    G1 = G1,
+    G2 = G2,
+    ScalarField = Fr,
+    G1BaseField = Fq,
+    G2BaseField = Fq3,
+    TargetField = Fq6,
+);