build(deps): bump futures-core from 0.3.7 to 0.3.8
Bumps [futures-core](https://github.com/rust-lang/futures-rs) from 0.3.7 to 0.3.8.
- [Release notes](https://github.com/rust-lang/futures-rs/releases)
- [Changelog](https://github.com/rust-lang/futures-rs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/futures-rs/compare/0.3.7...0.3.8)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
dependabot-preview[bot]