Fix parameters import

Author: jlubken

src/test_app.py

@@ -5,7 +5,8 @@
 import numpy as np
 
 from app import (projection_admits, alt)
-from penn_chime.models import sir, sim_sir, sim_sir_df, Parameters
+from penn_chime.models import sir, sim_sir, sim_sir_df
+from penn_chime.parameters import Parameters
 from penn_chime.presentation import display_header, new_admissions_chart
 from penn_chime.settings import DEFAULTS
 from penn_chime.defaults import RateLos