remove hardcoded secret key, rely on env variable

app/worker.py

@@ -9,7 +9,7 @@ from apscheduler.triggers.cron import CronTrigger
 basedir = os.path.abspath(os.path.dirname(__file__))
 
 app = Flask(__name__)
-app.config['SECRET_KEY'] = 'HwG55rpe83jcaglifXm8NuF4WEeXyJV4'
+app.config['SECRET_KEY'] = os.environ['SECRET_KEY']
 app.config['SQLALCHEMY_DATABASE_URI'] =\
            'sqlite:///' + os.path.join(basedir, os.environ['SQLITE_DB'])
 app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False