Add Piotr Chabelski as an ambassador (#1623)

Author: Gedochao

_data/ambassadors.yml

@@ -67,3 +67,11 @@
   linkedin: https://www.linkedin.com/in/luksow/
   mastodon: https://fosstodon.org/@luksow
   meetup: https://www.meetup.com/ScalaWAW/
+
+- name: Piotr Chabelski
+  description: Product Manager of the Scala 3 Compiler, maintainer of Scala CLI, Scala tooling engineer & enthusiast.
+  image: /ambassadors/piotr.jpg
+  city: Warsaw, Poland
+  discord: gedochao
+  github: Gedochao
+  linkedin: https://www.linkedin.com/in/piotr-ch/