chore(package.json): use SPDX license expression

See https://spdx.org/licenses/

Author: btford

package.json

@@ -19,7 +19,7 @@
     "quality"
   ],
   "author": "Brian Ford <[email protected]>",
-  "license": "Apache 2.0",
+  "license": "Apache-2.0",
   "bugs": {
     "url": "https://github.com/angular/angular-hint/issues"
   },