Read MQTT password from file

[cybcon]

Feature:

• MQTT password can now be read from a file by using the MQTT_PASSWORD_FILE variable to specify a file that contains the password.

Other changes:

• Adding a (better) documentation on how to contribute to the project (CONTRIBUTE.md)
• Adding a docker compose example (docker-compose.yaml)
• Enhance Copyright year in license file and documentation
• Increase application version
• Enhance Python unittest documentation
• Optimize code validation pipeline by adding an additional requirements.txt
• Cleanup requirments.txt
• Optimize Python doc