Using SPM to resolve dependencies in terminal resulting a Xcode project without any Scheme

So I build a dummy package that goes as simple as this

import PackageDescription

let package = Package(
    name: "PTSwift",
    platforms: [
        .macOS(.v10_14),
    ],
    products: [
        .library(
            name: "PTSwift",
            targets: ["PTSwift"]),
    ],
    dependencies: [
            .package(url: "https://github.com/Quick/Quick.git", from: "4.0.0"),
            .package(url: "https://github.com/Quick/Nimble.git", from: "9.2.0"),
    ],
    targets: [
        .target(
            name: "PTSwift",
            dependencies: []),
        .testTarget(
            name: "PTSwiftTests",
            dependencies: ["PTSwift", "Quick", "Nimble"]),
    ],
    swiftLanguageVersions: [.v5]
)

And then drag and drop it onto Xcode(13.1), which shows me a normal project with one default scheme.

Then I close Xcode, go back to the terminal, and run

swift package resolve
swift test

Everything works as expected.

But when I open the package with Xcode again, the scheme is missing. I also try the "auto-generate scheme now" button on the scheme management dialog, nothing happened.

Why?