refactor: remove safe-buffer dependency (#1023)

Co-authored-by: Ulises Gascón <ulisesgascongonzalez@gmail.com>

Author: bjohansebas

index.js

@@ -13,7 +13,6 @@
  * @private
  */
 
-var Buffer = require('safe-buffer').Buffer
 var cookie = require('cookie');
 var crypto = require('crypto')
 var debug = require('debug')('express-session');

package.json

@@ -16,7 +16,6 @@
     "depd": "~2.0.0",
     "on-headers": "~1.0.2",
     "parseurl": "~1.3.3",
-    "safe-buffer": "5.2.1",
     "uid-safe": "~2.1.5"
   },
   "devDependencies": {