Disable the unimplemented "create" arg for uploads

I never got around to implementing the create-and-upload behavior for
the file attachment command. I'll do it later, but for now I'm disabling
the code to quiet down the compiler warnings.

src/cli.rs

@@ -30,8 +30,9 @@ pub enum Commands {
     UploadRelease {
         #[arg()]
         tag_name: String,
-        #[arg(short, long)]
-        create: bool,
+        // TODO: implement create-and-upload as a single command invocation
+        // #[arg(short, long)]
+        // create: bool,
         #[arg()]
         files: Vec<String>,
     },