Add GitHub sponsors link to NPM.

Author: Borewit

package.json

@@ -6,6 +6,10 @@
     "name": "Borewit",
     "url": "https://github.com/Borewit"
   },
+  "funding": {
+    "type": "github",
+    "url": "https://github.com/sponsors/Borewit"
+  },
   "scripts": {
     "clean": "del-cli lib/**/*.js lib/***.js.map *.d.ts test/**/*.d.ts test/**/*.js test/**/*.js.map .nyc_output",
     "build": "npm run compile",