Add docker publish workflow

[LaithSaq]

Short Summary of the Issue

Currently, there is no existing GitHub Action for publishing Docker images, which is necessary for deployment automation.

Changes made to Resolve the Issue

• Added a GitHub Action to automate Docker image publishing, ensuring a streamlined deployment process.
• Renamed the CI workflow for testing to improve clarity.

Instructions for Testers

Once this has been merged, please test the following:

• Verify that the Docker image publishing GitHub Action runs successfully:
  • Ensure that a new Docker image is built and published correctly.
  • Confirm that the published image is available in docker hub Miaplaza/Middlemail.
• As a regression, verify that existing workflows are not affected:
  • Ensure that the other CI workflow remain functional with the new name.
    • Check that the testing process still executes as expected.

Release Notes

Technical improvements:

• Added GitHub Action for Docker image publishing, streamlining deployment automation.

Checklist

• Tested No, the current setup only triggers the job after pushing/merging into master releasing from a tag.
• Checked for typos.
• I have made sure that the Release Notes are understandable to a non-developer without the context of this Issue & Merge Request.
• I have made sure that the Instructions for Testers are self-contained.
• I have self-reviewed the Description and the Changes of this Pull Request.
• Has been approved by a developer.
• Has been approved by a reviewer.