use_running_average and deterministic default to None

PiperOrigin-RevId: 896146741

Author: Cristian Garcia

flax/nnx/nn/normalization.py

@@ -290,7 +290,7 @@ def __init__(
     self,
     num_features: int,
     *,
-    use_running_average: bool | None = False,
+    use_running_average: bool | None = None,
     axis: int = -1,
     momentum: float = 0.99,
     epsilon: float = 1e-5,

flax/nnx/nn/stochastic.py

@@ -73,7 +73,7 @@ def __init__(
     rate: float,
     *,
     broadcast_dims: Sequence[int] = (),
-    deterministic: bool | None = False,
+    deterministic: bool | None = None,
     rng_collection: str = 'dropout',
     rngs: rnglib.Rngs | rnglib.RngStream | None = None,
   ):