Add @dukecat0 to volunteer list (#1134)

Author: dukecat0

README.md

@@ -444,6 +444,7 @@ pipx is maintained by a team of volunteers (in alphabetical order)
 
 - [Bernát Gábor](https://github.com/gaborbernat)
 - [Chad Smith](https://github.com/cs01) - co-lead maintainer
+- [Jason Lam](https://github.com/dukecat0)
 - [Matthew Clapp](https://github.com/itsayellow) - co-lead maintainer
 - [Tzu-ping Chung](https://github.com/uranusjr)