Swift 5.1.2 "the package dependency graph could not be resolved"

[JoakimCh]

I wanted to try the "GL window" example in the latest Swift version and for some reason all the other libraries loads ok, but not ANY of the CGLFW versions. Which is totally confusing to someone new to Swift like me. I don't even think the error message is correct, Github has that tag, but Swift is blind to this. Hopefully a quick fix...?
My package file

// swift-tools-version:5.1

import PackageDescription

let package = Package(
  name: "glWindow",
  products: [
    .executable(name: "glWindow", targets: ["glWindow"]),
  ],
  dependencies: [
    .package(url: "https://github.com/SwiftGL/OpenGL.git", from: "3.0.0"),
    .package(url: "https://github.com/SwiftGL/Math.git", from: "2.0.0"),
    .package(url: "https://github.com/SwiftGL/Image.git", from: "2.0.0"),
    .package(url: "https://github.com/SwiftGL/CGLFW3Linux.git", from: "1.0.1"),
  ],
  targets: [
    .target(name: "glWindow", dependencies: ["SGLMath", "SGLImage", "SGLOpenGL", "CGLFW3Linux"], path: "."),
  ]
)

Results in:

joakim: swift build
Updating https://github.com/SwiftGL/Image.git
Updating https://github.com/SwiftGL/OpenGL.git
Updating https://github.com/SwiftGL/Math.git
Updating https://github.com/SwiftGL/CGLFW3Linux.git
error: the package dependency graph could not be resolved; unable to find any available tag for the following requirements:
    https://github.com/SwiftGL/CGLFW3Linux.git @ 1.0.1..<2.0.0

[jkolb]

Try it with the original https://github.com/SwiftGL/CGLFW3 from what I remember it was updated such that it makes the Linux versions mostly obsolete.

[JoakimCh]

@jkolb That was the first version of the library that I tried, all 3 versions have the same fault. I guess I should use an old version of Swift as a solution or try to figure out how to update the library to be compatible myself. As a person new to Swift this is not very encouraging, but I guess I will figure something out.

UPDATE:
Using .branch("master") I got a better error message describing the problem:

error: package at 'https://github.com/SwiftGL/CGLFW3.git' @ 77087c95d0b6fee26551b27efb6f04b845cb09cd is using Swift tools version 3.1.0 which is no longer supported; consider using '// swift-tools-version:5.1' to specify the current tools version

I guess I will just fork the library and tweak it to work then.

[jkolb]

Looks like something related to this https://forums.swift.org/t/problem-with-new-package-manager-system-library-targets/16358. I attempted to build CGLFW3 by itself and it gave me this "warning: system packages are deprecated; use system library targets instead". I haven't kept up with the latest changes in the Swift Package Manager so I'm just as clueless as you are about what might need to get done to update this. If you find a solution I would be happy to merge any PRs that might be needed.

[JoakimCh]

Adding // swift-tools-version:5.1 to its package file fixed it in my fork. But I failed getting my OpenGL example to work with the SwiftGL libraries. The best solution for me was to use a version which is actually maintained (and contains CGLFW3 and other needed libraries): https://github.com/GothStar/SwiftGL