Fixes 256 - ValueError mutable default

Fixes issue EleutherAI#256. Error message:

> ValueError: mutable default <class 'elk.training.train.Elicit'> for field run_template is not allowed: use
default_factory

elk/training/sweep.py

@@ -6,7 +6,6 @@
 from transformers import AutoConfig
 
 from ..evaluation import Eval
-from ..extraction import Extract
 from ..files import memorably_named_dir, sweeps_dir
 from ..plotting.visualize import visualize_sweep
 from ..training.eigen_reporter import EigenReporterConfig
@@ -52,12 +51,7 @@ class Sweep:
     name: str | None = None
 
     # A bit of a hack to add all the command line arguments from Elicit
-    run_template: Elicit = Elicit(
-        data=Extract(
-            model="<placeholder>",
-            datasets=("<placeholder>",),
-        )
-    )
+    run_template: Elicit = field(default_factory=Elicit.Default)    
 
     def __post_init__(self, add_pooled: bool):
         if not self.datasets:

elk/training/train.py

@@ -13,6 +13,7 @@
 
 from ..metrics import evaluate_preds, to_one_hot
 from ..run import Run
+from ..extraction import Extract
 from ..training.supervised import train_supervised
 from ..utils.typing import assert_type
 from .ccs_reporter import CcsReporter, CcsReporterConfig
@@ -34,6 +35,15 @@ class Elicit(Run):
     cross-validation. Defaults to "single", which means to train a single classifier
     on the training data. "cv" means to use cross-validation."""
 
+    @staticmethod 
+    def Default():
+        return Elicit(
+            data=Extract(
+                model="<placeholder>",
+                datasets=("<placeholder>",),
+            )
+        )
+
     def create_models_dir(self, out_dir: Path):
         lr_dir = None
         lr_dir = out_dir / "lr_models"