Bump Azure.AI.OpenAI.Assistants in /dotnet

Bumps [Azure.AI.OpenAI.Assistants](https://github.com/Azure/azure-sdk-for-net) from 1.0.0-beta.3 to 1.0.0-beta.4.
- [Release notes](https://github.com/Azure/azure-sdk-for-net/releases)
- [Commits](Azure/azure-sdk-for-net@Azure.AI.OpenAI.Assistants_1.0.0-beta.3...Azure.AI.OpenAI.Assistants_1.0.0-beta.4)

---
updated-dependencies:
- dependency-name: Azure.AI.OpenAI.Assistants
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

dotnet/Directory.Packages.props

@@ -7,7 +7,7 @@
   <ItemGroup>
     <PackageVersion Include="Azure.AI.ContentSafety" Version="1.0.0" />
     <PackageVersion Include="Azure.AI.OpenAI" Version="1.0.0-beta.17" />
-    <PackageVersion Include="Azure.AI.OpenAI.Assistants" Version="1.0.0-beta.3" />
+    <PackageVersion Include="Azure.AI.OpenAI.Assistants" Version="1.0.0-beta.4" />
     <PackageVersion Include="Azure.Identity" Version="1.12.0" />
     <PackageVersion Include="Azure.Monitor.OpenTelemetry.Exporter" Version="1.2.0" />
     <PackageVersion Include="Azure.Search.Documents" Version="11.5.1" />