Add the simplest possible test for teqp with AbstractModel

src/tests/catch_test_vdWEOS1.cxx

@@ -0,0 +1,9 @@
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/catch_approx.hpp>
+using Catch::Approx;
+
+#include "teqp/cpp/teqpcpp.hpp"
+
+TEST_CASE("Simplest case","[vdW1]") {
+    auto model = teqp::cppinterface::make_model(R"(  {"kind": "vdW1", "model": {"a": 1, "b": 2}} )"_json);
+}