Bump the dotnet group with 1 update (#49628)

Bumps OpenAI from 2.5.0 to 2.6.0

---
updated-dependencies:
- dependency-name: OpenAI
  dependency-version: 2.6.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: dotnet
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/ai/quickstarts/snippets/image-generation/openai/ImagesOpenAI.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="OpenAI" Version="2.5.0" />
+    <PackageReference Include="OpenAI" Version="2.6.0" />
     <PackageReference Include="Microsoft.Extensions.AI.OpenAI" Version="9.4.0-preview.1.25207.5" />
     <PackageReference Include="Microsoft.Extensions.Configuration" Version="9.0.10" />
     <PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="9.0.10" />