chore: vouch Jakub-Vacek (#4559)

Adds [Jakub-Vacek](https://github.com/Jakub-Vacek) to the list of
vouched outside contributors so their PRs aren't auto-closed by the
vouch check.

Author: isshaddad

.github/VOUCHED.td

@@ -27,4 +27,5 @@ saasjesus
 brentshulman-silkline
 Leafgard
 Rohan170603
-NERLOE
+NERLOE
+Jakub-Vacek