sponsor: adding google cloud as a silver sponsor (#15080)

Author: znemski

data/events/2025/washington-dc/main.yml

@@ -181,6 +181,8 @@ sponsors:
     level: community
   - id: devitjobs
     level: community
+  - id: googlecloud
+    level: silver
  #  url: http://mysponsor.com/?campaign=me # Use this if you need to over-ride a sponsor URL.
 
 sponsors_accepted : "yes" # Whether you want "Become a XXX Sponsor!" link