chore(deps): bump libssz family to 0.2.2 (lambdaclass#394)

## 🗒️ Description / Motivation
- Bumps the `libssz` family of dependencies from `0.2.1` to `0.2.2`.
- A new `0.2.2` release is available; this keeps us on the latest patch.
- Pins the intended version explicitly in the workspace manifest instead
of leaving it implicit in the lockfile.

## What Changed
- `Cargo.toml` — `libssz`, `libssz-derive`, `libssz-merkle`,
`libssz-types` requirement changed from `"0.2"` to `"0.2.2"`.
- `Cargo.lock` — corresponding `libssz*` entries updated `0.2.1` →
`0.2.2`.

## Correctness / Behavior Guarantees
- No source changes; purely a dependency patch bump.
- Caret requirement `"0.2.2"` raises the floor while still allowing
compatible patch updates (`>=0.2.2, <0.3.0`).

## Tests Added / Run
- `make fmt` — clean
- `make lint` — clean
- `make test` — 62 passed, 8 pre-existing `AttestationTooFarInFuture`
failures in `forkchoice_spectests` (verified identical on `main`,
unrelated to this change).

## Related Issues / PRs
- N/A

## ✅ Verification Checklist

- [x] Ran `make fmt` — clean
- [x] Ran `make lint` (clippy with `-D warnings`) — clean
- [ ] Ran `cargo test --workspace --release` — 8 pre-existing forkchoice
spectest failures unrelated to this change (same on `main`)

Author: pablodeymo

Cargo.lock

@@ -59,10 +59,10 @@ clap = { version = "4.3", features = ["derive", "env"] }
 leansig = { git = "https://github.com/leanEthereum/leanSig" }
 
 # SSZ implementation
-libssz = "0.2"
-libssz-derive = "0.2"
-libssz-merkle = "0.2"
-libssz-types = "0.2"
+libssz = "0.2.2"
+libssz-derive = "0.2.2"
+libssz-merkle = "0.2.2"
+libssz-types = "0.2.2"
 
 # Build-time version info
 vergen-git2 = { version = "9", features = ["rustc"] }