ci(backend): build and scan docker image

[aadil96]

build and scan docker image with in the gha workflow

[what-the-diff]

PR Summary

• Improvement of Backend Application Deployment Process
  This update introduces new stages into our automated system (GitHub Actions workflow). One of these stages is dedicated to constructing a Docker image for our backend application. Docker is a tool that helps us package and distribute our application efficiently.

• Introduction of a Security Feature - Trivy Vulnerability Scanner
  The update also enhances our app's security by integrating Trivy, a scanner that detects potential threats within the Docker image of our backend application. It targets mainly severe ("CRITICAL" and "HIGH" level) vulnerabilities. It importantly also excludes vulnerabilities that do not have a known fix yet, helping us to focus on solvable issues.

[github-actions]

Package	Line Rate	Complexity	Health
.	99%	0	✔
Summary	99% (136 / 138)	0	✔