Add Postgres support

[sunank200]

Please describe the feature you'd like to see
Support for Postgres is not there.

Describe the solution you'd like
Add Postgres support

Acceptance Criteria

• All checks and tests in the CI should pass
• Unit tests (90% code coverage or more)
• Integration tests (if the feature relates to a new database or external service)
• Example DAG
• Docstrings in reStructuredText for each of methods, classes, functions and module-level attributes (including Example DAG on how it should be used)
• Exception handling in case of errors
• Logging (are we exposing useful information to the user? e.g. source and destination)
• Improve the documentation (README, Sphinx, and any other relevant)
• How to use Guide for the feature (example)