chore: bump etcd-client from 0.8.3 to 0.8.4

Bumps [etcd-client](https://github.com/etcdv3/etcd-client) from 0.8.3 to 0.8.4.
- [Release notes](https://github.com/etcdv3/etcd-client/releases)
- [Commits](https://github.com/etcdv3/etcd-client/compare/0.8.3...v0.8.4)

---
updated-dependencies:
- dependency-name: etcd-client
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

core/Cargo.toml

@@ -21,7 +21,7 @@ bs58 = "0.4.0"
 chrono = { version = "0.4.11", features = ["serde"] }
 crossbeam-channel = "0.5"
 dashmap = { version = "5.1.0", features = ["rayon", "raw-api"] }
-etcd-client = { version = "0.8.3", features = ["tls"]}
+etcd-client = { version = "0.8.4", features = ["tls"]}
 fs_extra = "1.2.0"
 histogram = "0.6.9"
 itertools = "0.10.3"