c++20 seems to be not supporting constexpr vector - is my installation incorrect

I just finished upgrading my compiler to C++20 on ubuntu 20.04. g++ version gives me the following output :

c++ (Ubuntu 10.3.0-1ubuntu1~20.04) 10.3.0

I am trying the following code as suggested on stackoverflow

constexpr int f() {
    std::vector<int> v = {1, 2, 3};
    return v.size();
}

int main() {
    static_assert(f() == 3);
}

But I am getting the following error :

error: variable ‘v’ of non-literal type ‘std::vector<int>’ in ‘constexpr’ function

Am I going wrong somewhere. Or is my installation incorrect