Verify Dockerfile in github actions with hadolint prior to Docker Push

[tillkuhn]

github.com/hadolint/hadolint
Maybe use existing marketplace action, or do it yourself e.g.

$curl -sS -L https://github.com/hadolint/hadolint/releases/download/v1.19.0/hadolint-Linux-x86_64 \
--output /tmp/hadolint && chmod u+x /tmp/hadolint

$ /tmp/hadolint Dockerfile && echo "Dockerfile OK"
Dockerfile:27 DL3025 Use arguments JSON notation for CMD and ENTRYPOINT arguments

Sample output:

Dockerfile:27 DL3025 Use arguments JSON notation for CMD and ENTRYPOINT arguments