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_importer/Cargo.toml

@@ -11,7 +11,7 @@ clap = { version = "4.4", features = ["derive"] }
 gpui.workspace = true
 indexmap = { version = "1.6.2", features = ["serde"] }
 log.workspace = true
-palette = { version = "0.7.3", default-features = false, features = ["std"] }
+palette.workspace = true
 rust-embed.workspace = true
 schemars = { workspace = true, features = ["indexmap"] }
 serde.workspace = true