Hoist itertools dependency to workspace level (#8417)

This PR hoists the `itertools` dependency to the workspace level.

Release Notes:

- N/A

crates/theme/Cargo.toml

@@ -23,7 +23,7 @@ fs.workspace = true
 futures.workspace = true
 gpui.workspace = true
 indexmap = { version = "1.6.2", features = ["serde"] }
-itertools = { version = "0.11.0", optional = true }
+itertools = { workspace = true, optional = true }
 palette = { version = "0.7.3", default-features = false, features = ["std"] }
 parking_lot.workspace = true
 refineable.workspace = true