change MIN_boost_version

ubuntu version 20.04 is no longer supported.
The minimum boost version used for freecad is now 1.74 (ubuntu 22.04) https://launchpad.net/ubuntu/jammy/+package/libboost-system-dev

src/Mod/TechDraw/App/DrawPage.h

@@ -23,7 +23,7 @@
 #ifndef DrawPage_h_
 #define DrawPage_h_
 
-#include <boost_signals2.hpp>
+#include <boost/signals2.hpp>
 
 #include <App/DocumentObject.h>
 #include <App/PropertyStandard.h>

src/Mod/TechDraw/App/DrawView.h

@@ -23,7 +23,7 @@
 #ifndef DrawView_h_
 #define DrawView_h_
 
-#include <boost_signals2.hpp>
+#include <boost/signals2.hpp>
 #include <QCoreApplication>
 #include <QRectF>
 

src/Mod/TechDraw/Gui/MDIViewPage.cpp

@@ -37,7 +37,7 @@
 #include <QPrintDialog>
 #include <QPrintPreviewDialog>
 #include <QPrinter>
-#include <boost_signals2.hpp>
+#include <boost/signals2.hpp>
 #include <cmath>
 #endif
 

src/Mod/TechDraw/Gui/QGIView.h

@@ -25,7 +25,7 @@
 
 #include <Mod/TechDraw/TechDrawGlobal.h>
 
-#include <boost_signals2.hpp>
+#include <boost/signals2.hpp>
 
 #include <QColor>
 #include <QFont>

src/Mod/TechDraw/Gui/ViewProviderDrawingView.cpp

@@ -24,7 +24,7 @@
 #include "PreCompiled.h"
 
 #ifndef _PreComp_
-#include <boost_signals2.hpp>
+#include <boost/signals2.hpp>
 #include <boost/signals2/connection.hpp>
 #endif
 

src/Mod/TechDraw/Gui/ViewProviderDrawingView.h

@@ -26,7 +26,7 @@
 
 #include <Mod/TechDraw/TechDrawGlobal.h>
 
-#include <boost_signals2.hpp>
+#include <boost/signals2.hpp>
 
 #include <Gui/ViewProviderDocumentObject.h>
 #include <Mod/TechDraw/App/DrawView.h>

src/Mod/TechDraw/Gui/ViewProviderPage.cpp

@@ -30,7 +30,7 @@
 # include <QPointer>
 # include <QTextStream>
 
-# include <boost_signals2.hpp>
+# include <boost/signals2.hpp>
 # include <boost/signals2/connection.hpp>
 #endif
 

src/Mod/TechDraw/Gui/ViewProviderPage.h

@@ -27,7 +27,7 @@
 #include <QObject>
 #include <QPointer>
 
-#include <boost_signals2.hpp>
+#include <boost/signals2.hpp>
 
 #include <App/PropertyUnits.h>
 #include <Gui/ViewProviderDocumentObject.h>