Change to GPL 3.0 or later.

Author: thejpster

Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 authors = ["Jonathan 'theJPster' Pallant <[email protected]>"]
 edition = "2018"
 description = "Common BIOS code and API for all Neotron systems."
+license = "GPL-3.0-or-later"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html