Update dotnet-core-desktop.yml

Update setup-msbuild to v1.0.2 to resolve add-path issue.

Author: joshkempner

.github/workflows/dotnet-core-desktop.yml

@@ -72,4 +72,4 @@ jobs:
 
     # Add  MSBuild to the PATH: https://github.com/microsoft/setup-msbuild
     - name: Setup MSBuild.exe
-      uses: microsoft/setup-msbuild@2008f912f56e61277eefaac6d1888b750582aa16
+      uses: microsoft/setup-msbuild@v1.0.2