physicalterminal.cpp: fix std::min template deduction under Qt6

QVector::size() (== QList::size() under Qt6) returns qsizetype
(64-bit), while 'level' is a plain int. std::min(level,
m_real_terminal.size()-1) therefore tries to deduce a single T
from two different argument types, which fails - GCC reports it
against the unrelated std::min(initializer_list<T>) overload,
but the real issue is the type mismatch between the two-argument
candidates. Under Qt5, QVector::size() returned int, so this
compiled fine.
Force T=int explicitly via std::min<int>(...) and cast size()
down to int (physical terminal counts are always tiny), matching
the pattern already used safely elsewhere in the codebase (e.g.
qetgraphicstableitem.cpp).

sources/TerminalStrip/physicalterminal.cpp

@@ -131,7 +131,7 @@ bool PhysicalTerminal::setLevelOf(const QSharedPointer<RealTerminal> &terminal,
 	if (i >= 0)
 	{
 #if QT_VERSION >= QT_VERSION_CHECK(5,14,0)
-		m_real_terminal.swapItemsAt(i, std::min(level, m_real_terminal.size()-1));
+		m_real_terminal.swapItemsAt(i, std::min<int>(level, static_cast<int>(m_real_terminal.size())-1));
 #else
 		auto j = std::min(level, m_real_terminal.size()-1);
 		std::swap(m_real_terminal.begin()[i], m_real_terminal.begin()[j]);