fixing sensor tests (not working version)

imports/sensors/concordia_file_report.py

@@ -10,10 +10,12 @@ from pathlib import Path
 import pandas as pd
 from city_model_structure.attributes.concordia_energy_sensor import ConcordiaEnergySensor
 
+
 class ConcordiaFileReport:
   def __init__(self, city, end_point, base_path, db_file):
 
     self._city_object = []
+    self._city_objects_cluster = []
     self._sensors = []
     self._sensor_point = {}
     self._city = city