fix(package): update sequelize to version 5.21.11

Closes #53

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
     "joi": "14.0.4",
     "lodash": "4.17.11",
     "semver": "5.6.0",
-    "sequelize": "4.41.1"
+    "sequelize": "5.21.11"
   },
   "devDependencies": {
     "@jagql/framework": "5.6.13",