Fix the use of deprecated set-output command in image release workflow

[eljog]

set-output command used in the action workflows are deprecated

images/.github/workflows/push.yml

Line 34 in 1167ec1

run: echo "::set-output name=tag::$(echo "${{ github.ref }}" | grep -oP 'refs/tags/\K(.+)')"

replace it according to this blog post

Warnings on action runs:

The `set-output` command is deprecated and will be disabled soon.
Please upgrade to using Environment Files. For more information see:
 https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/