Require Node 10 for building.

#110

Author: RubenVerborgh

package.json

@@ -6,7 +6,7 @@
   "browser": "browser/index.js",
   "module": "module/index.js",
   "engines": {
-    "node": ">=8.0.0"
+    "node": ">=10.0.0"
   },
   "bin": "./bin/solid-auth-client.js",
   "files": [