RLN: Update proof generation according to updated circuit

[rymnc]

In https://github.com/Rate-Limiting-Nullifier/rln_circuits/pull/2 the rln circuit has been updated to include the rln_identifier in calculation of the external_nullifier

Below is a list of functions that need to be updated -

• https://github.com/vacp2p/zerokit/blob/master/rln/src/protocol.rs#L252
• https://github.com/vacp2p/zerokit/blob/master/rln/src/protocol.rs#L430

It looks like we don't need to update the verification side since the circuit is still taking in the same inputs.