feat: also exclude tests

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/dagger-rust/src/source.rs

@@ -89,6 +89,7 @@ impl RustSource {
 
         let mut excludes = self.exclude.clone();
         excludes.push("**/src".to_string());
+        excludes.push("**/test".to_string());
 
         let directory = self.client.host().directory_opts(
             source.display().to_string(),