Update to node16 and replace `setOutput`

[kuhnroyal]

node12 is deprecated:

The following actions uses node12 which is deprecated and will be forced to run on node16: swinton/commit@bfa68d879ec57187f2c5bf616158433763f05f06. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/

setOutput is also deprecated:

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/

[kuhnroyal]

I found https://github.com/tohgarashi/verified-commit for others looking for a solution