Fix lsp config deserialization case

It should have been in kebab-case, but it was the default snake_case.

helix-term/src/config.rs

@@ -13,6 +13,7 @@ pub struct Config {
 }
 
 #[derive(Default, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
 pub struct LspConfig {
     pub display_messages: bool,
 }