Fix import statement for IJEPA class

Author: fcogidi

mmlearn/tasks/__init__.py

@@ -1,7 +1,7 @@
 """Modules for pretraining, downstream and evaluation tasks."""
 
 from mmlearn.tasks.contrastive_pretraining import ContrastivePretraining
-from mmlearn.tasks.ijepa_pretraining import IJEPA
+from mmlearn.tasks.ijepa import IJEPA
 from mmlearn.tasks.zero_shot_classification import ZeroShotClassification
 from mmlearn.tasks.zero_shot_retrieval import ZeroShotCrossModalRetrieval