♻️ XmlRenderSettings::ProhibitDtd is obsolete in netstandard 2.0

Author: fluffynuts

src/log4net/Config/XmlConfigurator.cs

@@ -721,7 +721,7 @@ static private void InternalConfigure(ILoggerRepository repository, Stream confi
                                         // is obsolete: 'Use XmlReaderSettings.DtdProcessing property instead.'
 #if NETSTANDARD1_3 // TODO DtdProcessing.Parse not yet available (https://github.com/dotnet/corefx/issues/4376)
 					settings.DtdProcessing = DtdProcessing.Ignore;
-#elif !NET_4_0 && !MONO_4_0
+#elif !NET_4_0 && !MONO_4_0 && !NETSTANDARD2_0
 					settings.ProhibitDtd = true;
 #else
 					settings.DtdProcessing = DtdProcessing.Ignore;