Added GitHub Copilot project to release solution file (#3468)

Author: dmytrostruk

dotnet/agent-framework-release.slnf

@@ -6,6 +6,7 @@
       "src\\Microsoft.Agents.AI.Abstractions\\Microsoft.Agents.AI.Abstractions.csproj",
       "src\\Microsoft.Agents.AI.AGUI\\Microsoft.Agents.AI.AGUI.csproj",
       "src\\Microsoft.Agents.AI.Anthropic\\Microsoft.Agents.AI.Anthropic.csproj",
+      "src\\Microsoft.Agents.AI.GithubCopilot\\Microsoft.Agents.AI.GithubCopilot.csproj",
       "src\\Microsoft.Agents.AI.AzureAI.Persistent\\Microsoft.Agents.AI.AzureAI.Persistent.csproj",
       "src\\Microsoft.Agents.AI.AzureAI\\Microsoft.Agents.AI.AzureAI.csproj",
       "src\\Microsoft.Agents.AI.CopilotStudio\\Microsoft.Agents.AI.CopilotStudio.csproj",