message: [snarky] use [u8; 32] for the digest of the circuit
diff: @@ -12,7 +12,7 @@ pub trait GateVector<Field: FftField> {
  fn create() -> Self;
  fn add(&mut self, gate: CircuitGate<Field>);
  fn get(&self, idx: usize) -> CircuitGate<Field>;
  - fn digest(&self) -> Vec<u8>;
  + fn digest(&self) -> [u8; 32];
  }
  /** A row indexing in a constraint system.
  @@ -206,7 +206,7 @@ enum Circuit<Field, RustGates> {
  /** Once finalized, a circuit is represented as a digest
  and a list of gates that corresponds to the circuit.
  */
  - Compiled(Vec<u8>, RustGates),
  + Compiled([u8; 32], RustGates),
  }
  /** The constraint system. */
  