Update test options

Author: joefarebrother

csharp/ql/test/query-tests/Security Features/CWE-639/WebFormsTests/options

@@ -1 +1,3 @@
-semmle-extractor-options: /r:System.Collections.Specialized.dll ${testdir}/../../../../resources/stubs/System.Web.cs
+semmle-extractor-options: /nostdlib /noconfig
+semmle-extractor-options: --load-sources-from-project:${testdir}/../../../../resources/stubs/_frameworks/Microsoft.NETCore.App/Microsoft.NETCore.App.csproj
+semmle-extractor-options: ${testdir}/../../../../resources/stubs/System.Web.cs