Add specific warning for when database connectors is not found #58
Description
Is your feature request related to a problem? Please describe.
When installing PyMEOS, no database connector is installed by default. So, when using PyMEOS to connect to MobilityDB, it can be confusing why the connector is not found when intuitively it should be automatically installed with PyMEOS.
Describe the solution you'd like
A clearer message (instead of the python "ModuleNotFound" error message), stating that the connector is not installed and you have to install it manually.