[DBBackupRotation] Change shebang and update config filename

pica-db-backup-rotation/start_rotation.py

-#!/usr/bin/python3
+#!/usr/bin/env python3
 import os
 import sys
 import json
@@ -7,7 +7,7 @@ from crontab import CronTab
 # Setting constants
 BACKUP_FOLDER = '/backup'
 CONFIG_FOLDER = '/config'
-CONFIG_FILE = 'backup_data.json'
+CONFIG_FILE = 'backup_config.json'
 PATH_TO_CONFIG = CONFIG_FOLDER + '/' + CONFIG_FILE
 
 # Checks if the config file and folders can be accessed