(chore): upgrade versions to latest

Author: fern-api[bot]

fern/apis/api/generators.yml

@@ -86,7 +86,7 @@ groups:
   csharp-sdk:
     generators:
       - name: fernapi/fern-csharp-sdk
-        version: 1.9.29
+        version: 1.9.31
         disable-examples: true
         github:
           repository: VapiAI/server-sdk-csharp