Bump version number to 1.76.0

Jamroot

@@ -144,7 +144,7 @@ import option ;
 import tools/boost\_install/boost-install ;
 
 path-constant BOOST_ROOT : . ;
-constant BOOST_VERSION : 1.75.0 ;
+constant BOOST_VERSION : 1.76.0 ;
 constant BOOST_JAMROOT_MODULE : $(__name__) ;
 
 # Allow subprojects to simply `import config : requires ;` to get access to the requires rule