ci: update to new output format on GH actions

[georglauterbach]

Description

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

Type of change

• Update to component due to deprecation notice

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas

[casperklein]

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• If necessary I have added tests that prove my fix is effective or that my feature works

Are you sure? 😄

[georglauterbach]

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• If necessary I have added tests that prove my fix is effective or that my feature works

Are you sure? smile

Not sure I follow, haha :D What did I miss?:)

[casperklein]

I have made corresponding changes to the documentation

You did not make changes to the docs for example ;-)

[georglauterbach]

I have made corresponding changes to the documentation

You did not make changes to the docs for example ;-)

I always read this like "if there changes to the docs necessary, I did them" 🙈 I can adjust the description though 🙃