Bump sequelize from 4.32.2 to 5.15.1

Bumps [sequelize](https://github.com/sequelize/sequelize) from 4.32.2 to 5.15.1.
- [Release notes](https://github.com/sequelize/sequelize/releases)
- [Commits](sequelize/sequelize@v4.32.2...v5.15.1)

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

Author: dependabot[bot]

package-lock.json

@@ -37,7 +37,7 @@
     "no-kafka": "^3.2.10",
     "node-schedule": "^1.3.0",
     "pg": "^7.3.0",
-    "sequelize": "^4.21.0",
+    "sequelize": "^5.15.1",
     "superagent": "^3.8.0",
     "tc-core-library-js": "appirio-tech/tc-core-library-js.git#v2.4",
     "winston": "^2.4.0"