♻️ refactor(cli): remove unused credential file

- remove credential file parameters
- use GmailClient instance instead

src/cli/label_cli.rs

@@ -1,12 +1,12 @@
 use clap::Parser;
-use cull_gmail::{Error, Labels};
+use cull_gmail::{Error, GmailClient};
 
 #[derive(Debug, Parser)]
 pub struct LabelCli {}
 
 impl LabelCli {
-    pub async fn run(&self, credential_file: &str) -> Result<(), Error> {
-        let _ = Labels::new(credential_file, true).await?;
+    pub async fn run(&self, client: GmailClient) -> Result<(), Error> {
+        client.show_label();
         Ok(())
     }
 }