rename ext to integrations

Author: apoorvkh

docs/source/examples/scripts/lightning_train.py

@@ -10,7 +10,7 @@
 from transformers import AutoModelForCausalLM, AutoTokenizer
 
 import torchrunx
-from torchrunx.ext.lightning import TorchrunxClusterEnvironment
+from torchrunx.integrations.lightning import TorchrunxClusterEnvironment
 
 class GPT2CausalLMDataset(Dataset):
     def __init__(self, text_dataset):

src/torchrunx/ext/__init__.py

@@ -0,0 +1 @@
+"""Utilities for integrations with other libraries."""