chore: bump default Cardano version to '8.9.0' in e2e test

Author: jpraynaud

mithril-test-lab/mithril-end-to-end/src/main.rs

@@ -57,7 +57,7 @@ pub struct Args {
     cardano_epoch_length: f64,
 
     /// Cardano node version
-    #[clap(long, default_value = "8.7.3")]
+    #[clap(long, default_value = "8.9.0")]
     cardano_node_version: String,
 
     /// Epoch at which hard fork to the latest Cardano era will be made (starts with the latest era by default)