chore(deps): bump @polkadot/api from 1.4.2 to 1.5.1
Bumps [@polkadot/api](https://github.com/polkadot-js/api) from 1.4.2 to 1.5.1.
- [Release notes](https://github.com/polkadot-js/api/releases)
- [Changelog](https://github.com/polkadot-js/api/blob/master/CHANGELOG.md)
- [Commits](https://github.com/polkadot-js/api/commits/v1.5.1)
Signed-off-by: dependabot-preview[bot] <[email protected]>