Bump minor version for a breaking release

As of this version, the package will error upon loading if used with
Julia > 1.7. Previously it could be loaded but didn't work properly with
later Julia versions. To be safe, we're making this a breaking release.
It should be a largely user-invisible change though, as BinaryBuilder is
generally not used as a package dependency.

Project.toml

@@ -1,7 +1,7 @@
 name = "BinaryBuilder"
 uuid = "12aac903-9f7c-5d81-afc2-d9565ea332ae"
 authors = ["Elliot Saba <[email protected]>"]
-version = "0.5.9"
+version = "0.6.0"
 
 [deps]
 ArgParse = "c7e460c6-2fb9-53a9-8c5b-16f535851c63"