Copilot Chat: Update SK version to 0.16.230615.1-preview (microsoft#1553

)

### Motivation and Context
<!-- Thank you for your contribution to the semantic-kernel repo!
Please help reviewers and future users, providing the following
information:
  1. Why is this change required?
  2. What problem does it solve?
  3. What scenario does it contribute to?
  4. If it fixes an open issue, please link to the issue here.
-->
When using qDrant as the memory store for CC, we are seeing an error
caused by searching.
### Description
<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->
Update Copilot Chat SK dependency to version 0.16.230615.1-preview to
mitigate a qDrant related error.

### Contribution Checklist
<!-- Before submitting this PR, please make sure: -->
- [ ] The code builds clean without any errors or warnings
- [ ] The PR follows SK Contribution Guidelines
(https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
- [ ] The code follows the .NET coding conventions
(https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions)
verified with `dotnet format`
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

samples/apps/copilot-chat-app/webapi/CopilotChatWebApi.csproj

@@ -11,13 +11,13 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Azure.Cosmos" Version="3.34.0" />
-    <PackageReference Include="Microsoft.SemanticKernel" Version="0.15.230531.5-preview" />
-    <PackageReference Include="Microsoft.SemanticKernel.Connectors.AI.OpenAI" Version="0.15.230531.5-preview" />
-    <PackageReference Include="Microsoft.SemanticKernel.Connectors.Memory.AzureCognitiveSearch" Version="0.15.230531.5-preview" />
-    <PackageReference Include="Microsoft.SemanticKernel.Connectors.Memory.Qdrant" Version="0.15.230531.5-preview" />
-    <PackageReference Include="Microsoft.SemanticKernel.Skills.MsGraph" Version="0.15.230531.5-preview" />
-    <PackageReference Include="Microsoft.SemanticKernel.Skills.OpenAPI" Version="0.15.230531.5-preview" />
-    <PackageReference Include="Microsoft.SemanticKernel.Skills.Web" Version="0.15.230531.5-preview" />
+    <PackageReference Include="Microsoft.SemanticKernel" Version="0.16.230615.1-preview" />
+    <PackageReference Include="Microsoft.SemanticKernel.Connectors.AI.OpenAI" Version="0.16.230615.1-preview" />
+    <PackageReference Include="Microsoft.SemanticKernel.Connectors.Memory.AzureCognitiveSearch" Version="0.16.230615.1-preview" />
+    <PackageReference Include="Microsoft.SemanticKernel.Connectors.Memory.Qdrant" Version="0.16.230615.1-preview" />
+    <PackageReference Include="Microsoft.SemanticKernel.Skills.MsGraph" Version="0.16.230615.1-preview" />
+    <PackageReference Include="Microsoft.SemanticKernel.Skills.OpenAPI" Version="0.16.230615.1-preview" />
+    <PackageReference Include="Microsoft.SemanticKernel.Skills.Web" Version="0.16.230615.1-preview" />
     <PackageReference Include="Azure.Extensions.AspNetCore.Configuration.Secrets" Version="1.2.2" />
     <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.21.0" />
     <PackageReference Include="Microsoft.Identity.Web" Version="2.11.1" />