Patch/feat/GitHub actions cicd

[gideonmaina]

Description

This PR is a patch to PR #162 in an aim to make the workflow leaner by reducing verbosity

Additional changes.

1. Fix missing DOCKERHUB_REPO name in dokku deploy command.
2. Added a guard rail for manual dispatch. This is to prevent production deploys from a staging image beta-pr-. i.e. only deploy from master refs.

Potential changes

1. Have test job in its own worflow
2. Update branch protection rules to have a minimum number of reviewers to approve production job runs (deploy) as anyone with write access can trigger production deploy atm.