message: Replace obsolete functions of QSslSocket
  The QSslSocket::setDefaultCaCertificates() and
  QSslSocket::systemCaCertificates() member functions are obsolete since
  Qt 5.12.
diff: #include <QNetworkReply>
  #include <QNetworkRequest>
  #include <QSslCertificate>
  +#include <QSslConfiguration>
  #include <QSslError>
  -#include <QSslSocket>
  #include <QStringList>
  #include <QTextDocument>
  #include <QUrlQuery>
  @@ -448,9 +448,9 @@ void PaymentServer::LoadRootCAs(X509_STORE* _store)
  certList = QSslCertificate::fromPath(certFile);
  // Use those certificates when fetching payment requests, too:
  - QSslSocket::setDefaultCaCertificates(certList);
  + QSslConfiguration::defaultConfiguration().setCaCertificates(certList);
  } else
  - certList = QSslSocket::systemCaCertificates();
  + certList = QSslConfiguration::systemCaCertificates();
  int nRootCerts = 0;
  const QDateTime currentTime = QDateTime::currentDateTime();
  