Bump sequelize from 5.21.3 to 5.21.11

Bumps [sequelize](https://github.com/sequelize/sequelize) from 5.21.3 to 5.21.11.
- [Release notes](https://github.com/sequelize/sequelize/releases)
- [Commits](https://github.com/sequelize/sequelize/compare/v5.21.3...v5.21.11)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -79,7 +79,7 @@
     "passwords": "^1.3.1",
     "pg": "^7.18.2",
     "redis": "^3.0.2",
-    "sequelize": "^5.21.3",
+    "sequelize": "^5.21.11",
     "smooth-scroll": "^16.1.2",
     "statsy": "~0.2.0",
     "stripe": "^8.24.0",