Bugfix: actions dockerhub push

[scrasmussen]

SOURCE: Soren Rasmussen, NSF NCAR

DESCRIPTION OF CHANGES:

• Move from Docker Buildx to build and push the docker image to basic CLI docker commands. The old version might be failing due to buildx taking too long and github times-out because there hasn't been output to the terminal in a set amount of time.

TESTS CONDUCTED:

• PR will test and push to dtcenter/ccpp-scm:latest-test docker tag. Once the Github action succeeds the last commit of this PR should be removed before merging.

[scrasmussen]

Unfortunately (or fortunately for security) the secrets.DOCKERHUB_TOKEN variable isn't defined in PRs, so the only way to test this is after it is merged into main. Thus this PR is ready for review