Adjusted type hint for load_and_concat_data

src/mdevaluate/system.py

@@ -1,6 +1,7 @@
 import abc
 from dataclasses import dataclass, field
 from subprocess import run
+from typing import Iterable
 
 import pandas as pd
 
@@ -44,7 +45,7 @@ class MDSystem(abc.ABC):
         run(["mv", hdf5_temp_file, hdf5_file])
 
 
-def load_and_concat_data(systems: list[MDSystem], key: str, verbose: bool = False):
+def load_and_concat_data(systems: Iterable[MDSystem], key: str, verbose: bool = False):
     data = []
     for system in systems:
         try: