nominate @tsctx to be a maintainer

[Uzlopak]

@tsctx is in my opinion a very active contributor.

He is providing for 5-6 months PRs to the undici project, which mostly get accepted:
https://github.com/nodejs/undici/pulls?q=author%3Atsctx+

He also provided atleast one PR to nodejs core to fix an issue undici
#2026 (comment)
nodejs/node#51526

I thereby nominate @tsctx for the maintainer team :)

[mcollina]

invited

[tsctx]

Thank you for inviting me to join undici team :)