update license to BUSL

Author: nooxx

package.json

@@ -2,7 +2,7 @@
   "name": "@kilnfi/sdk",
   "version": "1.2.1",
   "autor": "Kiln <[email protected]> (https://kiln.fi)",
-  "license": "MIT",
+  "license": "BUSL-1.1",
   "description": "JavaScript sdk for Kiln API",
   "main": "lib/kiln.js",
   "types": "lib/kiln.d.ts",