Fix call to random.randint to use integer arguments.

Python 3.12 will no longer convert float to integer arguments and instead will raise an error.

https://docs.python.org/3/whatsnew/3.12.html#changes-in-the-python-api
> Formerly, randrange(10.0) losslessly converted to randrange(10). Now, it raises a TypeError.

PiperOrigin-RevId: 723521435

tensorflow_federated/python/simulation/baselines/emnist/emnist_models.py

@@ -30,7 +30,7 @@ def __init__(
   ):
     self._initializer_type = initializer_type
     if base_seed is None:
-      base_seed = random.randint(1, 1e9)
+      base_seed = random.randint(1, 1_000_000_000)
     self._base_seed = base_seed
 
   def __call__(self):