fix(deps): update rust crate splines to v5

Author: renovate[bot]

Cargo.lock

@@ -21,7 +21,7 @@ slotmap = "1"
 downcast-rs = "2"
 indexmap = { version = "2", features = ["serde"] }
 num = { version = "0.4", features = ["serde"] }
-splines = { version = "4", features = ["serde"] }
+splines = { version = "5", features = ["serde"] }
 derive-where = "1"
 
 config = { version = "0.4.1", registry = "substrate", path = "../config" }