Update .gitlab-ci.yml file

.gitlab-ci.yml

 stages:
   - lint
   - test
-  # -build
+  - build
   # - deploy
 
 variables:
@@ -40,3 +40,18 @@ test:
     - echo "Running PyTests"
   after_script:
     - echo "Tests completed succesfully"
+
+build:
+  stage: build
+  image: docker:latest
+  services:
+    - docker:dind
+  before_script:
+    - echo "Building Docker image for commit:" ${CI_COMMIT_SHORT_SHA}
+    - echo "Logging in to Docker registry..."
+    - echo ${DOCKER_PASSWORD} | docker login -u ${DOCKER_USERNAME} --password-stdin ${DOCKER_REGISTRY}
+  script:
+    - echo "Building image..."
+  after_script:
+    - echo "Docker image pushed successfully!"
+