Fix max_length type in base_model.py (#138)

Co-authored-by: Nathan Habib <[email protected]>

Author: csarron

src/lighteval/models/base_model.py

@@ -259,7 +259,7 @@ def _init_max_length(self, max_length) -> int:
             int: Max length to use depending on the available args and config
         """
         if max_length is not None:
-            return max_length
+            return int(max_length)
         # Try to get the sequence length from the model config.
         seqlen_config_attrs = ("n_positions", "max_position_embeddings", "n_ctx")