Fix compilation with g++

src/mesh/Mesh.hpp

@@ -14,7 +14,7 @@ class Mesh : public std::enable_shared_from_this<Mesh<MeshDimension>>
 {
  public:
   static constexpr size_t Dimension = MeshDimension;
-  using Connectivity                = Connectivity<Dimension>;
+  using Connectivity                = ::Connectivity<Dimension>;
 
   using Rd = TinyVector<Dimension>;