I have this old networking code that uses a completion handler. Please refactor it to use modern Swift Concurrency with async/await.

The new function should be marked with `async throws` and return a `[Post]` object upon success. Also, include an example of how to call this new async function inside a `Task` with a `do-catch` block.

**Old Code:**
struct Post: Codable {
    let id: Int
    let title: String
}

func fetchPosts(completion: @escaping (Result<[Post], Error>) -> Void) {
    guard let url = URL(string: "https://api.example.com/posts") else { return }
    URLSession.shared.dataTask(with: url) { data, _, error in
        if let error = error { completion(.failure(error)); return }
        guard let data = data else { return }
        do {
            let posts = try JSONDecoder().decode([Post].self, from: data)
            completion(.success(posts))
        } catch {
            completion(.failure(error))
        }
    }.resume()
}