fix: deprecated gh actions functions

[kevholmes]

This attempts to resolve #96. Most of these errors being surfaced were coming from outdated Actions such as docker/login-action or docker/build-push-action. I've updated their major semantic versions to the latest available which should eliminate most errors. There were a couple related to us using set-output within the id: prep step in our build.yaml Workflow itself. I've removed the outputs that are not consumed (date, version) and converted the tags output var to utilize the newer style of echo "tags=${TAGS}" >> $GITHUB_OUTPUT.

[kevholmes]

I just noticed that the logic used to run a build on external PRs from a fork (like this one) fail to run the login to Dockerhub step due to the external fork not being able to utilize this repo's Secrets (expected.) I'll add in a conditional for that step to not run if this is a pull_request as it's unneeded there - we just want to make sure the project itself builds.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

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