Add a destructor which disposes all the remaining engine connections before deleting the sql object

cdplib/db_handlers/SQLHandler.py

@@ -103,6 +103,11 @@ class SQLHandler:
 
         self._engine = engine
 
+
+    def __del__(self):
+        self.dispose_engine()
+        self._log.info('SQL Handler has been destroyed')
+
     @property
     def _connection_params(self) -> dict:
         '''