Replace deprecated @paulmillr/qr with qr

# Feature Request

## Why it is needed

https://www.npmjs.com/package/@paulmillr/qr has a deprecation notice and recommends to migrate to https://www.npmjs.com/package/qr instead.

The package is installed in https://github.com/MetaMask/metamask-sdk/blob/104176ef9f6561d15454aa52436898adaf8410b2/packages/sdk/package.json#L57 and https://github.com/MetaMask/metamask-sdk/blob/104176ef9f6561d15454aa52436898adaf8410b2/packages/sdk-install-modal-web/package.json#L90

Start with packages/sdk/package.json at the referenced dependency entry, then inspect packages/sdk-install-modal-web/package.json at its entry. Replace the deprecated package with qr and check the repository's install, build, and test commands. Done means both manifests use qr successfully without introducing dependency or integration failures.

Written by the indexing model from the issue text.