[DENVER-2025] Adds CastAI as a gold sponsor for denver 2025 (#15306)

* Add CastAI as Gold Sponsor

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Co-authored-by: themightymuppet <[email protected]>
Co-authored-by: Keri Melich <[email protected]>

Author: denverdevopsdays

data/events/2025/denver/main.yml

@@ -81,6 +81,8 @@ organizer_email: "[email protected]"
 sponsors:
   - id: suse
     level: gold
+  - id: castai
+    level: gold
   - id: fairwinds
     level: supporter
   - id: code-talent