Bump orchestra/testbench from 6.3.0 to 6.4.0 (#97)

Bumps [orchestra/testbench](https://github.com/orchestral/testbench) from 6.3.0 to 6.4.0.
- [Release notes](https://github.com/orchestral/testbench/releases)
- [Changelog](https://github.com/orchestral/testbench/blob/6.x/CHANGELOG-6.x.md)
- [Commits](orchestral/testbench@v6.3.0...v6.4.0)

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: Kazi Ahmed <[email protected]>

Author: dependabot-preview[bot]