Method print_python_version_once

tests/test_with_catch/catch.cpp:89–97

private:
    void print_python_version_once() {
        if (printed_) {
            return;
        }
        printed_ = true;
        auto &os = Catch::cout();
        os << "[ PYTHON   ] " << Py_GetVersion() << '\n';
        os.flush();
    }

    bool printed_ = false;
};