vapor.json build config not loaded

[HazAT]

I am trying to link libz with my package, taken from this example
https://github.com/vapor/toolbox/blob/master/Tests/VaporToolboxTests/VaporConfigResources/Packages/Example-10.0.1/vapor.json

But the linker ignores it, so it fails to link Sentry, here is the file
https://github.com/getsentry/sentry-cocoa/blob/master/vapor.json
If I run locally swift build -Xlinker -lz it works fine for Sentry.

This is my Package.swift

import PackageDescription

let package = Package(
    name: "test",
    targets: [
        Target(name: "App"),
        Target(name: "Run", dependencies: ["App"]),
    ],
    dependencies: [
        .Package(url: "https://github.com/vapor/vapor.git", majorVersion: 2),
        .Package(url: "https://github.com/vapor/leaf-provider.git", majorVersion: 1),
        .Package(url: "https://github.com/getsentry/sentry-cocoa.git", "3.0.12")
    ],
    exclude: [
        "Config",
        "Database",
        "Public",
        "Resources",
    ]
)