Remove Qt 5.15 version checks

lib/previewplugin.cpp

@@ -82,11 +82,7 @@ QQmlContext* PreviewPlugin::context()
 void PreviewPlugin::highlight(const QTextDocument* doc) const
 {
     QTextCursor cursor;
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
-    const QStringList highlights = highlight().split(QLatin1Char(' '), QString::SkipEmptyParts);
-#else
     const QStringList highlights = highlight().split(QLatin1Char(' '), Qt::SkipEmptyParts);
-#endif
     for (const QString &text : highlights) {
         while (1) {
             cursor = doc->find(text, cursor);

lib/resultsmodel.cpp

@@ -52,11 +52,7 @@ public:
     ~SortProxyModel() override = default;
 
     void setQueryString(const QString &queryString) {
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
-        const QStringList words = queryString.split(QLatin1Char(' '), QString::SkipEmptyParts);
-#else
         const QStringList words = queryString.split(QLatin1Char(' '), Qt::SkipEmptyParts);
-#endif
         if (m_words != words) {
             m_words = words;
             invalidate();

lib/sourcesmodel.cpp

@@ -272,11 +272,7 @@ void SourcesModel::slotMatchesChanged(const QList<Plasma::QueryMatch>& l)
     // that do not
     // The rest are given the same preference as given by the runners.
     const QString simplifiedQuery = m_queryString.simplified();
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
-    const auto words = simplifiedQuery.splitRef(QLatin1Char(' '), QString::SkipEmptyParts);
-#else
     const auto words = simplifiedQuery.splitRef(QLatin1Char(' '), Qt::SkipEmptyParts);
-#endif
 
     QSet<QString> higherTypes;
     for (const QString &type : qAsConst(m_types)) {