Nova upgrade proposal

There is Tornado governance proposal for upgrade nova contract on Xdai chain.

Tests

1. Install dependencies:

    yarn install

2. Create .env file with actual values from .env.sample.

3. Run tests:

    yarn test

4. Run linter:

    yarn lint

Deploy

1. Check config.js for actual values. Take newNovaImpl address from README of repository.

2. Run deploy:

    npx hardhat run scripts/deploy.js --network mainnet