chore: Fix several style lints (#17488)

It's not comprehensive enough to start linting on `style` group, but
hey, it's a start.

Release Notes:

- N/A

crates/language_model/src/provider/anthropic.rs

@@ -58,7 +58,7 @@ pub struct AnthropicLanguageModelProvider {
     state: gpui::Model<State>,
 }
 
-const ANTHROPIC_API_KEY_VAR: &'static str = "ANTHROPIC_API_KEY";
+const ANTHROPIC_API_KEY_VAR: &str = "ANTHROPIC_API_KEY";
 
 pub struct State {
     api_key: Option<String>,