Update UnbrandedGeneratorVersion to 1.0.0-alpha.20250926.6 (Azure#52886)

Co-authored-by: Ubuntu <cloudtest@fd3cf2ffc00000Q.tkkhlgj2u51eln3mcb0lygmbye.dx.internal.cloudapp.net>

Author: azure-sdk

eng/Packages.Data.props

@@ -467,7 +467,7 @@
 
   <PropertyGroup>
     <TestProxyVersion>1.0.0-dev.20250922.2</TestProxyVersion>
-    <UnbrandedGeneratorVersion>1.0.0-alpha.20250926.3</UnbrandedGeneratorVersion>
+    <UnbrandedGeneratorVersion>1.0.0-alpha.20250926.6</UnbrandedGeneratorVersion>
     <AzureGeneratorVersion>1.0.0-alpha.20250922.2</AzureGeneratorVersion>
   </PropertyGroup>
 </Project>

eng/http-client-csharp-emitter-package-lock.json

@@ -2,7 +2,7 @@
   "main": "dist/src/index.js",
   "dependencies": {
     "client-plugin": "file:../../../../eng/packages/plugins/client",
-    "@typespec/http-client-csharp": "1.0.0-alpha.20250926.3"
+    "@typespec/http-client-csharp": "1.0.0-alpha.20250926.6"
   },
   "devDependencies": {
     "@azure-tools/typespec-client-generator-core": "0.60.0",

eng/http-client-csharp-emitter-package.json

@@ -38,7 +38,7 @@
     "dist/generator/**"
   ],
   "dependencies": {
-    "@typespec/http-client-csharp": "1.0.0-alpha.20250926.3"
+    "@typespec/http-client-csharp": "1.0.0-alpha.20250926.6"
   },
   "devDependencies": {
     "@azure-tools/azure-http-specs": "0.1.0-alpha.28",