Fix CI publish: replace apt-get nuget install with nuget/setup-nuget@v2 action

Agent-Logs-Url: https://github.com/dadhi/FastExpressionCompiler/sessions/d59ede86-adcb-458e-a2f2-0bc0ad41a8c4

Co-authored-by: dadhi <39516+dadhi@users.noreply.github.com>

Author: Copilot

.github/workflows/publish.yml

@@ -41,7 +41,7 @@ jobs:
 
       # The classic NuGet CLI is required because .nuspec files are not supported by `dotnet pack`.
       - name: Install NuGet CLI
-        run: sudo apt-get install -y nuget
+        uses: nuget/setup-nuget@v2
 
       - name: Build
         run: dotnet build -c:Release