chore(deps): bump the cargo group across 3 directories with 1 update

Bumps the cargo group with 1 update in the /examples/demo directory: [rustls](https://github.com/rustls/rustls).
Bumps the cargo group with 1 update in the /starters/rest-api directory: [rustls](https://github.com/rustls/rustls).
Bumps the cargo group with 1 update in the /starters/saas directory: [rustls](https://github.com/rustls/rustls).


Updates `rustls` from 0.23.15 to 0.23.18
- [Release notes](https://github.com/rustls/rustls/releases)
- [Changelog](https://github.com/rustls/rustls/blob/main/CHANGELOG.md)
- [Commits](rustls/rustls@v/0.23.15...v/0.23.18)

Updates `rustls` from 0.23.12 to 0.23.18
- [Release notes](https://github.com/rustls/rustls/releases)
- [Changelog](https://github.com/rustls/rustls/blob/main/CHANGELOG.md)
- [Commits](rustls/rustls@v/0.23.15...v/0.23.18)

Updates `rustls` from 0.23.12 to 0.23.18
- [Release notes](https://github.com/rustls/rustls/releases)
- [Changelog](https://github.com/rustls/rustls/blob/main/CHANGELOG.md)
- [Commits](rustls/rustls@v/0.23.15...v/0.23.18)

---
updated-dependencies:
- dependency-name: rustls
  dependency-type: indirect
  dependency-group: cargo
- dependency-name: rustls
  dependency-type: indirect
  dependency-group: cargo
- dependency-name: rustls
  dependency-type: indirect
  dependency-group: cargo
...

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