Docker CI: deprecated `set-output` command

[nsenave]

⚠️ warning in Docker workflow:

The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files.

https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/

- name: Set output
  run: echo "::set-output name={name}::{value}"

To be replaced with

- name: Set output
  run: echo "{name}={value}" >> $GITHUB_OUTPUT

[nsenave]

Fixed in develop #127