rust/keygen(deps): bump rand_core in /tools/ssh_keygen

Bumps [rand_core](https://github.com/rust-random/rand) from 0.6.4 to 0.9.3.
- [Release notes](https://github.com/rust-random/rand/releases)
- [Changelog](https://github.com/rust-random/rand/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-random/rand/commits)

---
updated-dependencies:
- dependency-name: rand_core
  dependency-version: 0.9.3
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

tools/ssh_keygen/Cargo.lock

@@ -10,7 +10,7 @@ anyhow = "1.0"
 clap = { version = "4.0", features = ["derive"] }
 ssh-key = { version = "0.6", features = ["ed25519", "rsa", "ecdsa", "rand_core"] }
 rand = "0.8"
-rand_core = "0.6"
+rand_core = "0.9"
 
 [dev-dependencies]
 tempfile = "3.0"