chore(deps): bump momento from 0.52.0 to 0.56.0 in /example/rust (#499)

Bumps [momento](https://github.com/momentohq/client-sdk-rust) from 0.52.0 to 0.56.0.
- [Release notes](https://github.com/momentohq/client-sdk-rust/releases)
- [Changelog](https://github.com/momentohq/client-sdk-rust/blob/main/CHANGELOG.md)
- [Commits](v0.52.0...v0.56.0)

---
updated-dependencies:
- dependency-name: momento
  dependency-version: 0.56.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]