chore(deps): bump rand in /bots/echidnabot

Bumps [rand](https://github.com/rust-random/rand) in `/bots/echidnabot` from 0.10.2 to 0.10.3.


Updates `rand` from 0.10.2 to 0.10.3
- [Release notes](https://github.com/rust-random/rand/releases)
- [Changelog](https://github.com/rust-random/rand/blob/master/CHANGELOG.md)
- [Commits](rust-random/rand@0.10.2...0.10.3)

---
updated-dependencies:
- dependency-name: rand
  dependency-version: 0.10.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: cargo
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]