Port of https://github.com/go-gitea/gitea/pull/29205
Use a clearly defined "signing secret" for token signing.
(cherry picked from commit 8be198cdef0a486f417663b1fd6878458d7e5d92)
This change allows act_runner / actions_runner to use jwt tokens for
`ACTIONS_RUNTIME_TOKEN` that are compatible with
actions/upload-artifact@v4.
The official Artifact actions are now validating and extracting the jwt
claim scp to get the runid and jobid, the old artifact backend also
needs to accept the same token jwt.
---
Related to #28853
I'm not familar with the auth system, maybe you know how to improve this
I have tested
- the jwt token is a valid token for artifact uploading
- the jwt token can be parsed by actions/upload-artifact@v4 and passes
their scp claim validation
Next steps would be a new artifacts@v4 backend.
~~I'm linking the act_runner change soonish.~~
act_runner change to make the change effective and use jwt tokens
<https://gitea.com/gitea/act_runner/pulls/471>
