fix: set correct author ref

Author: ChrisKujawa

chaos-days/blog/authors.yml

@@ -1,9 +1,9 @@
 zell:
   name: Christopher Kujawa
   title: Chaos Engineer @ Zeebe
-  url: https://github.com/zelldon
+  url: https://github.com/ChrisKujawa
   page: true
-  image_url: https://github.com/zelldon.png
+  image_url: https://github.com/ChrisKujawa.png
 nicolas:
   name: Nicolas Pepin-Perreault
   title: Senior Software Engineer @ Zeebe