Feature Request: Allow .CHECKSUM and .TIMESTAMP variables to be used in cmds

[andreynering]

Discussed in #1734

^{Originally posted by pavetok August 4, 2024}
Hi everyone,

First of all, thanks for the great tool!

I want to build docker image only when sources changed, but {{.CHECKSUM}} empty in cmds :(

Why is that?

image:
  sources:
    - ./**
  status:
    - docker image inspect my/app:{{.CHECKSUM}}
  cmds:
    - docker build . -t my/app:latest -t my/app:{{.CHECKSUM}}
```</div>