chore: deploy contracts and replace mumbai with amoy

[cedoor]

Description

This PR deploys the latest version of the contracts and replaces Polygon Mumbai (deprecated) with Amoy.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have run yarn format and yarn lint without getting any errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[sripwoud]

How were all the contracts deployed?
Isn't the README in packages/contracts outdated? It refers to a deploy:semaphore script but I don't see it defined in packages/contracts/package.json.
I see there is a deploy:semaphore as a hardhat task in the hardhat semaphore plugin but @semaphore-protocol/hardhat isn't a dep of @semaphore-protocol/contracts either?

[cedoor]

How were all the contracts deployed?

I just created a Notion document with all the steps here: https://pse-team.notion.site/Deploy-new-Semaphore-contracts-2480c6767c3c4be58a36db55e448c8af. It's a starting point to write a guide on the Semaphore documentation website.

Isn't the README in packages/contracts outdated?

It is! The right command is yarn deploy. Let me update it!