Update .gitlab-ci.yml file

stages:          # List of stages for jobs, and their order of execution

  - build

  - test

  - deploy

build-job:       # This job runs in the build stage, which runs first.

  stage: build

unit-test-job:   # This job runs in the test stage.

  stage: test    # It only starts when the job in the build stage completes successfully.

  script:

    - echo "Running unit tests... This will take about 60 seconds."

    - echo "Running unit tests... "

    - sleep 60

    - echo "Code coverage is 90%"

lint-test-job:   # This job also runs in the test stage.

  stage: test    # It can run at the same time as unit-test-job (in parallel).

  script:

    - echo "Linting code... This will take about 10 seconds."

    - sleep 10

    - echo "No lint issues found."

deploy-job:      # This job runs in the deploy stage.

  stage: deploy  # It only runs when *both* jobs in the test stage complete successfully.

  script:

    - echo "Deploying application..."

    - echo "Application successfully deployed."

    - echo "python tests/test_flip_image.py"