Remove GitLab Build Dependency

Question

I have created a GitLab automated CI/CD build process that looks something like this:

And the .gitlab-ci.yml file looks like this (removed actual commands since they're not important to this question):

stages:
  - build
  - test
  - deploy
build-windows:
  stage: build
  before_script:
    - ...
  script:
    - ...
  artifacts:
    paths:
      - ...
    expire_in: 3 month
  tags:
    - windows
build-linux-ubuntu:
  stage: build
  before_script:
    - ...
  script:
    - ...
  artifacts:
    paths:
      - ...
    expire_in: 3 month
  tags:
    - linux
    - ubuntu
test-windows:
  stage: test
  before_script:
    - ...
  script:
    - ...
  after_script:
    - ...
  tags:

windows

test-linux-ubuntu:
  stage: test
  before_script:
    - ...
  after_script:
    - ...
  tags:
    - linux
    - ubuntu
deploy-windows:
  stage: deploy
  before_script:
    - ...
  script:
    - ...
  artifacts:
    paths:
      - ...
  after_script:
  tags:
    - windows
deploy-linux-ubuntu:
  stage: deploy
  before_script:
    - ...
  script:
    - ...
  artifacts:
    paths:
      - ...
    expire_in: 3 month
  after_script:
    - ...
  tags:
    - linux
    - ubuntu

Now this has the downside of Linux taking longer to build/test/deploy than Windows, so the Windows job finishes much quicker and just sits waiting for the Linux job to complete. Then once both have completed, it moves on to the next step. However, the Windows and Linux jobs are completely independent of one another.

How can I get GitLab to build both Windows and Linux in parallel, without the cross-dependency? Something like this: