Fix the license field in Cargo.toml to be valid SPDX

Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.8"
 authors = ["Jonathan Kelley"]
 edition = "2018"
 description = "Core functionality for Dioxus - a concurrent renderer-agnostic Virtual DOM for interactive user experiences"
-license = "MIT/Apache-2.0"
+license = "MIT OR Apache-2.0"
 repository = "https://github.com/DioxusLabs/dioxus/"
 homepage = "https://dioxuslabs.com"
 documentation = "https://dioxuslabs.com"