add a "browser" field so jsPDF works with parcel 2

Author: HackbrettXXX

package.json

@@ -5,6 +5,7 @@
   "description": "PDF Document creation from JavaScript",
   "main": "dist/jspdf.node.min.js",
   "module": "dist/jspdf.es.min.js",
+  "browser": "dist/jspdf.es.min.js",
   "files": [
     "dist",
     "types/index.d.ts",