Fix#30923
(cherry picked from commit effb405cae88474c27f5c8322a2627019af1cf64)
Signed-off-by: Gergely Nagy <forgejo@gergo.csillger.hu>
Conflicts:
- modules/setting/oauth2.go
Conflicted due to different ways of logging. Since the log
message is removed anyway, resolved by removing it.
- modules/setting/oauth2_test.go
Manually copied the test added by Gitea.
- routers/install/install.go
Not a conflict per se, but adjusted to use NewJwtSecret().
Port of https://github.com/go-gitea/gitea/pull/29205
Use a clearly defined "signing secret" for token signing.
(cherry picked from commit 8be198cdef0a486f417663b1fd6878458d7e5d92)
