refactor: fix deprecation up to Qt 6

Signed-off-by: Sefa Eyeoglu <contact@scrumplex.net>

launcher/Commandline.cpp

@@ -47,7 +47,7 @@ QStringList splitArgs(QString args)
             if (cchar == '\\')
                 escape = true;
             else if (cchar == inquotes)
-                inquotes = 0;
+                inquotes = QChar::Null;
             else
                 current += cchar;
             // otherwise
@@ -480,4 +480,4 @@ void Parser::getPrefix(QString &opt, QString &flag)
 ParsingError::ParsingError(const QString &what) : std::runtime_error(what.toStdString())
 {
 }
-}
+}