New: Use ASP.NET Core instead of Nancy

Co-Authored-By: ta264 <ta264@users.noreply.github.com>

frontend/src/Store/Actions/addSeriesActions.js

@@ -125,6 +125,7 @@ export const actionHandlers = handleThunks({
     const promise = createAjaxRequest({
       url: '/series',
       method: 'POST',
+      dataType: 'json',
       contentType: 'application/json',
       data: JSON.stringify(newSeries)
     }).request;