Use SPDX-compatible license format

Author: thomcc

Cargo.toml

@@ -2,7 +2,7 @@
 name = "cmake"
 version = "0.1.48"
 authors = ["Alex Crichton <alex@alexcrichton.com>"]
-license = "MIT/Apache-2.0"
+license = "MIT OR Apache-2.0"
 readme = "README.md"
 keywords = ["build-dependencies"]
 repository = "https://github.com/rust-lang/cmake-rs"