Add firebase-tools permissions workaround

• Bump up the base image version to latest node-slim
• Add NPM user variable to root to address current permission issues in firebase-tools

Update README for artifact action changes

v1.3.1

updated readme (#40)

Add support for new GCP Key on Firebase Tools

Firebase tools now allows you to specify a GCP Service Key instead of a Token to deploy your changes. We now support passing in this key in replacement of Firebase Token.

Create option for different directory

• Added in the ability to have Firebase.json in a different directory than root

Upgrade for latest Github Action systems

• A lot has changed since the initial beta of actions, this update will bring it up to par with the current way actions are configured.
• The example also shows how to pass a build artifact to the deployment job.

Entrypoint Syntax Fix

• Thanks to @uphy for the catch

GitHub Action for Firebase Initial Release

Update README

Further explanation on when you should use PROJECT_ID