Update README.md

Author: swhitty

README.md

@@ -17,7 +17,7 @@ IdentifiableContinuation can be installed by using Swift Package Manager.
 To install using Swift Package Manager, add this to the `dependencies:` section in your Package.swift file:
 
 ```swift
-.package(url: "https://github.com/swhitty/IdentifiableContinuation.git", .upToNextMajor(from: "0.3.0"))
+.package(url: "https://github.com/swhitty/IdentifiableContinuation.git", .upToNextMajor(from: "0.4.0"))
 ```
 
 # Usage