fix: can't use numpy stuff in defaults for now

hera_notebook_templates/notebooks/lststack.ipynb

@@ -159,7 +159,7 @@
     "freq_max: float = 0.0\n",
     "history: str = \"\"\n",
     "plot_every: int = 1\n",
-    "exception_for_zsq_above: float = np.inf  # Raise an exception if any baseline has a zsq greater than this. Useful for flagging weird behaviour for validation.\n",
+    "exception_for_zsq_above: float = 1e20  # Raise an exception if any baseline has a zsq greater than this. Useful for flagging weird behaviour for validation.\n",
     "\n",
     "# In-painting config\n",
     "inpaint_horizon: float = 1.0\n",