CI: Setup .NET 6 in packages-publishing workflow (#31155)

Author: alexslavr

.github/workflows/packages_publishing.yml

@@ -37,6 +37,11 @@ jobs:
         with:
           node-version: '20'
 
+      - name: Set up .NET
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: 6.0.x
+
       - name: Install dependencies
         run: npm install --no-audit --no-fund