Do not include timezone if DateTimeKind is Unspecified

DECREF'ing datetime timezone argument when DateTimeKind is Unspecified was causing `Fatal Python error: deallocating None` because the object was set to `Runtime.PyNone`.

Fixed the input to datetime constructor as we were passing milliseconds, where it should be microseconds.

src/runtime/converter.cs

@@ -292,15 +292,27 @@ internal static IntPtr ToPython(object value, Type type)
                 case TypeCode.DateTime:
                     var datetime = (DateTime)value;
 
-                    IntPtr dateTimeArgs = Runtime.PyTuple_New(8);
+                    var size = datetime.Kind == DateTimeKind.Unspecified ? 7 : 8;
+
+                    IntPtr dateTimeArgs = Runtime.PyTuple_New(size);
                     Runtime.PyTuple_SetItem(dateTimeArgs, 0, Runtime.PyInt_FromInt32(datetime.Year));
                     Runtime.PyTuple_SetItem(dateTimeArgs, 1, Runtime.PyInt_FromInt32(datetime.Month));
                     Runtime.PyTuple_SetItem(dateTimeArgs, 2, Runtime.PyInt_FromInt32(datetime.Day));
                     Runtime.PyTuple_SetItem(dateTimeArgs, 3, Runtime.PyInt_FromInt32(datetime.Hour));
                     Runtime.PyTuple_SetItem(dateTimeArgs, 4, Runtime.PyInt_FromInt32(datetime.Minute));
                     Runtime.PyTuple_SetItem(dateTimeArgs, 5, Runtime.PyInt_FromInt32(datetime.Second));
-                    Runtime.PyTuple_SetItem(dateTimeArgs, 6, Runtime.PyInt_FromInt32(datetime.Millisecond));
-                    Runtime.PyTuple_SetItem(dateTimeArgs, 7, TzInfo(datetime.Kind));
+
+                    // datetime.datetime 6th argument represents micro seconds
+                    var totalSeconds = datetime.TimeOfDay.TotalSeconds;
+                    var microSeconds = Convert.ToInt32((totalSeconds - Math.Truncate(totalSeconds)) * 1000000);
+                    if (microSeconds == 1000000) microSeconds = 999999;
+                    Runtime.PyTuple_SetItem(dateTimeArgs, 6, Runtime.PyInt_FromInt32(microSeconds));
+
+                    if (size == 8)
+                    {
+                        Runtime.PyTuple_SetItem(dateTimeArgs, 7, TzInfo(datetime.Kind));
+                    }
+
                     var returnDateTime = Runtime.PyObject_CallObject(dateTimeCtor, dateTimeArgs);
                     // clean up
                     Runtime.XDecref(dateTimeArgs);