Bump futures from 0.3.5 to 0.3.6 (RustScan#265)

Bumps [futures](https://github.com/rust-lang/futures-rs) from 0.3.5 to 0.3.6.
- [Release notes](https://github.com/rust-lang/futures-rs/releases)
- [Changelog](https://github.com/rust-lang/futures-rs/blob/master/CHANGELOG.md)
- [Commits](rust-lang/futures-rs@0.3.5...0.3.6)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: Bee <[email protected]>