TravisCI with GitHUB Package Repository (Only Pre Install and Install ) that generates .npmrc with github token

.travis.yml

language: node_js
node_js:
- 10

cache:
  directories:
  - node_modules

before_install:
- echo "INSTALL GLOBAL DEPENDENCIES"
- npm install -g serverless
- echo "BEFORE INSTALL - ADD PRIVATE REPO"
- npm config set registry https://npm.pkg.github.com/OWNER
- echo "GENERATING AUTH"
- echo //npm.pkg.github.com/:_authToken=$GITHUB_TOKEN > .npmrc

install:
- echo "INSTALL"
- npm install