chore: Update deps (fhevmjs, solidity contracts)

[amaury1093]

This PR updates some dependencies to make this repo work with the latest fhevm-go changes.

• [x] Update solidity to 0.8.20 (use latest fhevm/lib/THFE.sol)
• [x] Update fhevmjs to latest
  • [x] Update node-tfhe (i.e. tfhe-rs in WASM) to 0.5 (required by latest fhevm-go which also uses 0.5)
• [x] Update test/*.ts code to match upstream zama code

What I tested:

• [x] pnpm test
• [x] pnpm deploy:contracts and pnpm task:mint In both cases, when running with the latest fhevm-go changes (https://github.com/Inco-fhevm/fhevm-go/pull/3), I see the correct log:

  Info: [Caution!!] MockOpsFlag is enabled, decrypting ciphertext. Please make sure you're not using it in production. 
  Info: verifyCiphertext success ctHash 0xa2f2a944b6eaab8f098b3a2790e5a541d47e99103e9c569dd86b50015c8df2cd ctBytes64 1008000000000000417f3d1414cb7735ecb88effbbeb7904214f1357ab7b7780011dc8ce858fbd0a27afea656bfbd097f50059f64d86aff951298d722fcf4e6d 

I would love to have @TheoXD or @lovenoble to make sure it works, before merging.

[lovenoble]

It works well on my local.