build: Fix dependency for orchestrator-process (MaterializeInc#14541)

This commit adds the process feature for tokio to the
orchestrator-process crate. Some people were unable to build
Materialize from source because this feature was missing.

src/orchestrator-process/Cargo.toml

@@ -21,7 +21,7 @@ mz-secrets = { path = "../secrets" }
 serde_json = "1.0.85"
 scopeguard = "1.1.0"
 sysinfo = "0.25.3"
-tokio = "1.19.2"
+tokio = { version = "1.19.2", features = ["process"] }
 tracing = "0.1.36"
 
 [dev-dependencies]