(chore): upgrade versions to latest

Author: fern-api[bot]

fern/generators.yml

@@ -80,7 +80,7 @@ groups:
   csharp-sdk:
     generators:
       - name: fernapi/fern-csharp-sdk
-        version: 1.9.8
+        version: 1.9.15
         github:
           repository: ssoready/ssoready-csharp
           mode: pull-request