fix: restore #[test] and #[should_panic] attributes on panics_on_duplicate_agent_names

Lost in commit db00a5d4 when extracting tests from main.rs into cli.rs;
the line range used for the panics_on_duplicate_agent_names test in main.rs
started at the fn signature instead of the attribute line.

server/src/main.rs

@@ -872,6 +872,8 @@ async fn main() -> Result<(), std::io::Error> {
 mod tests {
     use super::*;
 
+    #[test]
+    #[should_panic(expected = "Invalid project.toml: Duplicate agent name")]
     fn panics_on_duplicate_agent_names() {
         let tmp = tempfile::tempdir().unwrap();
         let sk = tmp.path().join(".huskies");