tokio metrics

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/Cargo.toml

@@ -82,6 +82,7 @@ tikv-jemalloc-ctl.workspace = true
 tikv-jemalloc-sys.optional = true
 tikv-jemalloc-sys.workspace = true
 tokio.workspace = true
+tokio-metrics.workspace = true
 tracing-core.workspace = true
 tracing-subscriber.workspace = true
 tracing.workspace = true