Missing @ sign in readme.md

[NINI1988]

Gitlab-python-package-template/{{cookiecutter.package_name}}/README.md

Line 35 in eeb8fed

pip install {{cookiecutter.package_name}} --extra-index-url https://$GL_USERNAME:$GL_TOKEN{{cookiecutter.gitlab_host}}/api/v4/projects/{{cookiecutter.package_registry_repository_id}}/packages/pypi/simple

There should be an @ sign between $GL_TOKEN and {{cookiecutter.gitlab_host}}