Got this error, when following this solution: https://stackoverflow.com/a/61263653/20051894
'testTarget(name:dependencies:path:exclude:sources:resources:cSettings:cxxSettings:swiftSettings:linkerSettings:)' is unavailable
What is wrong?
targets: [
        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
        .target(
            name: "IkigaJSON",
            dependencies: [.product(name: "NIO", package: "swift-nio")]),
        .testTarget(
            name: "IkigaJSONTests",
            dependencies: [.target(name: "IkigaJSON")],
            resources: [
                .copy("Resources/test.txt")
            ]
        ),
    ]
)
