Skip linting of submodules

[Amxx]

Right now, the linter is configures as:

"lint": "npm run lint:js && npm run lint:sol",
"lint:fix": "npm run lint:js:fix && npm run lint:sol:fix",
"lint:js": "prettier --log-level warn --ignore-path .gitignore '**/*.{js,ts}' --check",
"lint:js:fix": "prettier --log-level warn --ignore-path .gitignore '**/*.{js,ts}' --write",
"lint:sol": "prettier --log-level warn --ignore-path .gitignore '{contracts,test}/**/*.sol' --check",
"lint:sol:fix": "prettier --log-level warn --ignore-path .gitignore '{contracts,test}/**/*.sol' --write",

While the solidity parts only run on contracts and test, the javascript/typescript part runs on all subfolders. This includes lib/* that contains the @openzeppelin/contracts submodules. These module include some javascript and typescript (tests, scripts, ...) thatare linted using a potentially different version/config of prettier.

This forces us to use the same prettier version/config as the main repos, which means we have to synchronise the updates.

We should configure linting in this repo so that lib/* is NOT linted.