Upgrade palette (#8506)

This fixes the compilation stck overflow here:
https://ogeon.github.io/2024/02/25/palette-0.7.5.html



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"] }
-palette = { version = "0.7.3", default-features = false, features = ["std"] }
+palette = { workspace = true, default-features = false, features = ["std"] }
 parking_lot.workspace = true
 refineable.workspace = true
 schemars = { workspace = true, features = ["indexmap"] }