test: fix typo in test-http2-invalidheaderfield.js

Psuedo -> Pseudo

PR-URL: https://github.com/nodejs/node/pull/39021


Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>