chore: remove unused serde and thiserror dependencies

Author: andygrove

native/spark-expr/Cargo.toml

@@ -33,10 +33,8 @@ datafusion = { workspace = true }
 chrono-tz = { workspace = true }
 num = { workspace = true }
 regex = { workspace = true }
-serde = { version = "1.0", features = ["derive"] }
 # preserve_order: needed for get_json_object to match Spark's JSON key ordering
 serde_json = { version = "1.0", features = ["preserve_order"] }
-thiserror = { workspace = true }
 datafusion-comet-common = { workspace = true }
 futures = { workspace = true }
 twox-hash = "2.1.2"