replace frob(6) by unitary_inverse in bls12

src/pairing/bls12/mod.rs

@@ -106,7 +106,7 @@ impl PG, P::Fp> for PairingVar
         // it work for curves with odd `P::X`.
         // Hence we implement the slower algorithm from Table 1 below.
 
-        let f1 = f.frobenius_map(6)?;
+        let f1 = f.unitary_inverse()?;
 
         f.inverse().and_then(|mut f2| {
             // f2 = f^(-1);