Merge pull request nestjs#2754 from nestjs/renovate/sequelize-5.x

fix(deps): update dependency sequelize to v5.15.0

Author: kamilmysliwiec

sample/07-sequelize/package.json

@@ -16,7 +16,7 @@
     "mysql2": "1.6.5",
     "reflect-metadata": "0.1.13",
     "rxjs": "6.5.2",
-    "sequelize": "5.14.0",
+    "sequelize": "5.15.0",
     "sequelize-typescript": "0.6.11",
     "typescript": "3.5.3"
   },