Upgrade to actions/checkout

[KyleJu]

Upgrade to actions/checkout@v3, which runs node16 by default. Resolve following warnings:

Node.js 12 actions are deprecated. For more information see: https://github.blog/changelog/2022-
09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/. Please 
update the following actions to use Node.js 16: actions/checkout, actions/checkout

[KyleJu]

Warnings on Update Docker image / build-and-push (push)

>> elgohr/Publish-Docker-Github-Action@master has been deprecated.
>> Please use elgohr/Publish-Docker-Github-Action@v4 for a blast in speed and security.
WARNING! Your password will be stored unencrypted in /github/home/.docker/config.json.
Configure a credential helper to remove this warning. See
https://docs.docker.com/engine/reference/commandline/login/#credentials-store

[KyleJu]

Will update the Warnings on Update Docker image / build-and-push (push) in a separate PR