Fix building Proximity.cpp with Qt6 and gcc 11.2 (#54)

* Fix building Proximity.cpp with Qt6 and gcc 11.2

Add <algorithm> header to the Proximity.cpp

* Fix formatting

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Co-authored-by: lightsilverberryfox <118631656+lightsilverberryfox@users.noreply.github.com>

src/foundation/Proximity.cpp

@@ -5,6 +5,7 @@
 
 #include <QLineF>
 #include <QPointF>
+#include <algorithm>
 
 Proximity::Proximity(const QPointF& p1, const QPointF& p2) {
   const double dx = p1.x() - p2.x();