fix: use spdx identifier for the license (#10)

Author: rytilahti

pyproject.toml

@@ -3,7 +3,7 @@ name = "kasa-crypt"
 version = "0.4.1"
 description = "Fast kasa crypt"
 authors = ["J. Nick Koston <[email protected]>"]
-license = "Apache Software License 2.0"
+license = "Apache-2.0"
 readme = "README.md"
 repository = "https://github.com/bdraco/kasa-crypt"
 classifiers = [