Switch to OpenZeppeling Base64 implementation

[haltakov]

Currently, we are using an implementation for Base64 encoding for the tokenURI copied from the Loot project: https://etherscan.io/address/0xff9c1b15b16263c61d017ee9f65c50e4ae0113d7#code#L1609

There is an open issue in OpenZeppeling to add an officially supported Base64 library: OpenZeppelin/openzeppelin-contracts#2859. There is a candidate PR with an active discussion, so the library may be added soon.

If OpenZeppeling adds a Base64 library, we should switch to it.

Remember to remove the exclude statement for the Base64 contract for the slither job in the CI:

bnomial-web3/.github/workflows/slither.yml

Line 56 in 7833cb7

slither . --exclude-dependencies --exclude-informational --compile-force-framework hardhat --filter-paths=contracts/Base64.sol --exclude=external-function

[kfischer-okarin]

OpenZeppelin/openzeppelin-contracts#2884

Seems it was merged 8 days ago... So maybe it's possible now?

[haltakov]

The Base64 contract is merged in the OpenZeppeling repo, but has not yet been released. The planned release version is 4.5. We need to wait just a little bit more :)

[haltakov]

During the implementation of the SVG rendering, I switched the Base64 implementation from the old one (copied from Loot) with the one from OpenZeppelin 4.5. After 4.5 is released, the switch should be very easy.