Bump github.com/golang-jwt/jwt to v5 (#25975)

Bump github.com/golang-jwt/jwt to v5 (#25975)

Bumping `github.com/golang-jwt/jwt` from v4 to v5.

`github.com/golang-jwt/jwt` v5 is bringing some breaking changes:

- standard `Valid()` method on claims is removed. It's replaced by
`ClaimsValidator` interface implementing `Validator()` method instead,
which is called after standard validation. Gitea doesn't seem to be
using this logic.
- `jwt.Token` has a field `Valid`, so it's checked in `ParseToken`
function in `services/auth/source/oauth2/token.go`

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Co-authored-by: Giteabot <teabot@gitea.io>