core: Add missing include

Author: jorisv

include/pinocchio/algorithm/constraints/coulomb-friction-cone.hpp

@@ -8,6 +8,7 @@
 #include "pinocchio/algorithm/constraints/fwd.hpp"
 #include "pinocchio/algorithm/constraints/cone-base.hpp"
 #include "pinocchio/math/fwd.hpp"
+#include "pinocchio/math/matrix.hpp"
 #include "pinocchio/math/comparison-operators.hpp"
 #include "pinocchio/utils/check.hpp"