Update .gitlab-ci.yml file

.gitlab-ci.yml

+image: docker:latest
+
+services:
+  - docker:dind
+
+variables:
+  # Define the Docker image name using the GitLab CI environment variables
+  IMAGE_NAME: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG
+
+before_script:
+  # Login to the GitLab Container Registry
+  - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
+
+stages:
+  - build
+
+build:
+  stage: build
+  script:
+    # Build the Docker image using the Dockerfile
+    - docker build -t $IMAGE_NAME .
+    # Push the Docker image to the GitLab Container Registry
+    - docker push $IMAGE_NAME