Can't import from Swift 5.3.2 / Xcode 12

[nicwaller]

Using Xcode 12 with Swift 5.3.2, I am unable to import this package.

package at 'https://github.com/TheCodedSelf/SwiftCron.git' @ d633279 is using Swift tools version 3.1.0 which is no longer supported; consider using '// swift-tools-version:5.3' to specify the current tools version

Steps to reproduce

1. Create a new Swift project in Xcode 12
2. File > Swift Packages > Add Package Dependency...
3. Paste URL https://github.com/TheCodedSelf/SwiftCron.git
4. Branch = master