fix: increase compute_immutable_files_signatures timeout

Author: dlachaume

mithril-test-lab/mithril-end-to-end/src/bin/load-aggregator/main.rs

@@ -239,7 +239,7 @@ async fn main_scenario(
             &parameters.cardano_db,
             current_epoch,
             &parameters.signers_fixture,
-            Duration::from_secs(60),
+            Duration::from_secs(120),
         )
         .await
         .unwrap();