Rewrite includes inside the library to use <catch2/> form

src/catch2/catch_generators_generic.hpp

@@ -7,8 +7,8 @@
 #ifndef TWOBLUECUBES_CATCH_GENERATORS_GENERIC_HPP_INCLUDED
 #define TWOBLUECUBES_CATCH_GENERATORS_GENERIC_HPP_INCLUDED
 
-#include "catch_generators.hpp"
-#include "catch_meta.hpp"
+#include <catch2/catch_generators.hpp>
+#include <catch2/catch_meta.hpp>
 
 namespace Catch {
 namespace Generators {