Fix/tweak the publishing workflow

[jordond]

Since automating a release to pub.dev isn't really possible on the CI, there should be a script that replicates that functionality. Pub.dev requires you to click a link to authenticate, which generates a token. But this token only lasts a few days. The old method was to encrypt and decrypt this token, I did not think about the expiration before.

Would need to:

• Install dependencies
• Lint files
• Run tests
• Build sample
• run semantic-release

This will require a GH_TOKEN env var.