fix(tower-sessions-core): disable parking_lot serde feature

It seems unused and it slows down the compilation of all crates that
depend on `parking_lot` (e.g. `tokio`).

Signed-off-by: Jalil David Salamé Messina <[email protected]>

Author: jalil-salame

tower-sessions-core/Cargo.toml

@@ -21,7 +21,7 @@ futures = { version = "0.3.28", default-features = false, features = [
   "async-await",
 ] }
 http = "1.0"
-parking_lot = { version = "0.12.1", features = ["serde"] }
+parking_lot = "0.12.1"
 rand = "0.9"
 serde = { version = "1.0.189", features = ["derive", "rc"] }
 serde_json = "1.0.107"