Change license from MIT to copyleft GNU AGPLv3

add author and license fields in package.json

package.json

 {
   "name": "squid",
+  "author": "Hugo Trentesaux <hugo@trentesaux.fr>",
+  "license": "AGPL-3.0",
   "version": "0.2.8",
   "private": true,
   "engines": {