fix: upgrade sequelize from 5.21.8 to 5.21.9

Snyk has created this PR to upgrade sequelize from 5.21.8 to 5.21.9.

See this package in NPM:
https://www.npmjs.com/package/sequelize

See this project in Snyk:
https://app.snyk.io/org/revjtanton/project/09a1968e-7b01-4032-9063-82f2e99f843e?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -57,7 +57,7 @@
     "nunjucks": "^3.2.1",
     "pg": "7.18.2",
     "random-words": "1.1.1",
-    "sequelize": "5.21.8",
+    "sequelize": "5.21.9",
     "snyk": "^1.316.2",
     "supertest": "4.0.2",
     "swagger-ui-express": "4.1.4",