Fix ps script in ci

Author: Ivan Kamkin

.github/workflows/net-framework.yml

@@ -38,7 +38,7 @@ jobs:
       run: |
             docker build . --file Dockerfile -t aspose-barcode-cloud-dotnet:test-nuget
             $containerId = docker run -di --rm aspose-barcode-cloud-dotnet:test-nuget
-            docker cp "$containerId:/packed/*.nupkg" NetFrameworkTests
+            docker cp "${containerId}:/packed/*.nupkg" NetFrameworkTests
 
     - name: Build test project
       run: msbuild NetFrameworkTests\Aspose.BarCode.Cloud.Sdk.NetFrameworkTests.csproj -restore -p:Configuration=Release