chore(deps): normalize engines' dev-dep tokio features (review 004 item 16)

All three engines' [dev-dependencies] tokio now carry the same feature
set: rt-multi-thread + macros + time + test-util (previously sqlite had
rt-multi-thread+macros+time, pg test-util only, mem rt+macros).
Dev-dep metadata only; each engine's tests verified green plus the
workspace build/clippy/fmt gates.

alkstore-postgres/Cargo.toml

@@ -20,4 +20,4 @@ tracing = "0.1"
 
 [dev-dependencies]
 alkstore-contract-suite = { path = "../alkstore-contract-suite" }
-tokio = { version = "1", features = ["test-util"] }
+tokio = { version = "1", features = ["rt-multi-thread", "macros", "time", "test-util"] }