message: misc: Fix Travis conditional build
  Not all environment variables that Travis set in build time are
  available to conditional build evaluation.
  Instead of using environment variables, we can condition on the fork
  attribute, which is false for branches in the main repo, and true
  for PRs sent from forks.
  Reference:
diff: @@ -44,7 +44,7 @@ jobs:
  - name: '@sentry/browser - browserstack integration tests'
  node_js: '12'
  script: scripts/browser-integration.sh
  - if: env(TRAVIS_SECURE_ENV_VARS) = true
  + if: fork = false
  - stage: Deploy
  name: '@sentry/packages - pack and zeus upload'
  node_js: '12'
  