build: cleanup solution file

Author: WeihanLi

dotnet-exec.slnx

@@ -6,7 +6,7 @@
   <Folder Name="/src/">
     <Project Path="src/dotnet-exec/dotnet-exec.csproj" />
     <Project Path="src/ReferenceResolver/ReferenceResolver.csproj" />
-    <Project Path="src\dotnet-exec-mcp\dotnet-exec-mcp.csproj" Type="Classic C#" />
+    <Project Path="src/dotnet-exec-mcp/dotnet-exec-mcp.csproj" />
   </Folder>
   <Folder Name="/tests/">
     <Project Path="tests/IntegrationTest/IntegrationTest.csproj" />