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

### Motivation and Context
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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" />