Update version to v2.5.0

- The default build used by `node`/`npm` no longer includes a bundled `Promise` polyfill. #79
  - The main benefit of this is that it reduces the build to ≈40% its previous size.
  - You can still use a version wiith the polyfill included. See `README.md` for instructions.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "clipboard-polyfill",
-  "version": "2.4.7",
+  "version": "2.5.0",
   "description": "A polyfill for the asynchronous clipboard API",
   "browser": "build/clipboard-polyfill.js",
   "types": "build/clipboard-polyfill.d.ts",