Add Cargo.toml features to fix compilation of individual crates

crates/buffer/Cargo.toml

@@ -25,6 +25,8 @@ smallvec = { version = "1.6", features = ["union"] }
 tree-sitter = "0.19.5"
 
 [dev-dependencies]
+gpui = { path = "../gpui", features = ["test-support"] }
+
 rand = "0.8.3"
 tree-sitter-rust = "0.19.0"
 unindent = "0.1.7"

crates/theme/Cargo.toml

@@ -8,7 +8,7 @@ gpui = { path = "../gpui" }
 anyhow = "1.0.38"
 indexmap = "1.6.2"
 parking_lot = "0.11.1"
-serde = { version = "1", features = ["derive"] }
+serde = { version = "1", features = ["derive", "rc"] }
 serde_json = { version = "1.0.64", features = ["preserve_order"] }
 serde_path_to_error = "0.1.4"
 toml = "0.5"