Add conditional for MSBuild setup on Windows

Author: iRodNCP

.github/workflows/main.yml

@@ -33,6 +33,7 @@ jobs:
           python-version: '3.10' 
 
       - name: Setup MSBuild
+        if: startsWith(matrix.os, 'windows')
         uses: microsoft/setup-msbuild@v1.1
 
       - name: Install dependencies