Only build new image when differen

[johnnyfleet]

Figure out a way to compare the Docker Hub latest version with one just created. To see if needs updating or not.

See if there is a way to use SHA256 or maybe tags.
Can we add a commit# to the docket image? Would that help though - its more if the contents have changed.

[johnnyfleet]

Check this link for some ideas to check if tag exists.

[johnnyfleet]

Probably need 2 actions.

One that runs on an update to my code and one that runs daily to check if there is a new upstream version.