chore(runner): return errors created by `connect` (#7222)
- Instead of creating errors via `google.golang.org/grpc`, use `connectrpc.com/connect`.
- This _avoids_ another dependency (still indirectly referenced in testing).
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7222
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>
authored by