Make license metadata SPDX compliant

Author: paolobarbolini

Cargo.toml

@@ -2,7 +2,7 @@
 name = "serde_urlencoded"
 version = "0.7.1" # bump in documentation link and in README on update
 authors = ["Anthony Ramine <[email protected]>"]
-license = "MIT/Apache-2.0"
+license = "MIT OR Apache-2.0"
 repository = "https://github.com/nox/serde_urlencoded"
 documentation = "https://docs.rs/serde_urlencoded/0.7.1/serde_urlencoded/"
 description = "`x-www-form-urlencoded` meets Serde"