Provide default seed value in TrainConfig, matching EvalConfig (#1315)

* Update config_utils.py

* lint

Author: mvpatel2000

llmfoundry/utils/config_utils.py

@@ -106,7 +106,9 @@ class TrainConfig:
     max_duration: Union[int, str] = MISSING
     eval_interval: Union[int, str] = MISSING
     max_seq_len: int = MISSING
-    seed: int = MISSING
+
+    # Seed
+    seed: int = 17
 
     # Precision
     precision: str = 'amp_bf16'