Use date-based tag rather than git SHA

[leonardehrenfried]

When I used the git SHA hashes originally I thought that I would be interested in knowing the exact version of an image. It turns out that in several years of using this image, I never looked at it and just want an identifier that is easy to parse for humans.

For this reason I'm switching to date-based tags. If you want to see what it looks like, you can take a look at OpenTripPlanner's repo: https://hub.docker.com/r/opentripplanner/opentripplanner/tags

[what-the-diff]

PR Summary

• New Container Date Tagging
  The process now includes an additional step where the software container gets a date tag. This label reflects the exact date and time when the container was created.

• Modified Docker Build Command
  We made changes to the 'Docker build' command, which is used to create software containers. Now, this command also includes the above-mentioned date tag in the image tag. This change allows you to identify the build's specific version by checking the date.