Avoid repeating the return type

src/base/rss/private/rss_parser.cpp

@@ -464,7 +464,7 @@ namespace
                 offset = parts[2].toInt(&ok[0]) * 3600;
                 int offsetMin = parts[3].toInt(&ok[1]);
                 if (!ok[0] || !ok[1] || offsetMin > 59)
-                    return QDateTime();
+                    return {};
                 offset += offsetMin * 60;
                 negOffset = (parts[1] == QLatin1String("-"));
                 if (negOffset)
@@ -494,7 +494,7 @@ namespace
                         for (int i = 0, end = zone.size(); (i < end) && !nonalpha; ++i)
                             nonalpha = !isalpha(zone[i]);
                         if (nonalpha)
-                            return QDateTime();
+                            return {};
                         // TODO: Attempt to recognize the time zone abbreviation?
                         negOffset = true;    // unknown time zone: RFC 2822 treats as '-0000'
                     }

src/base/rss/rss_autodownloadrule.cpp

@@ -68,7 +68,7 @@ namespace
         switch (static_cast<int>(triStateBool)) {
         case 0:  return false;
         case 1:  return true;
-        default: return QJsonValue();
+        default: return {};
         }
     }
 
@@ -159,7 +159,7 @@ QString computeEpisodeName(const QString &article)
 
     // See if we can extract an season/episode number or date from the title
     if (!match.hasMatch())
-        return QString();
+        return {};
 
     QStringList ret;
     for (int i = 1; i <= match.lastCapturedIndex(); ++i) {