chore(deps): bump mysql2 from 2.3.3 to 3.9.4

Bumps [mysql2](https://github.com/sidorares/node-mysql2) from 2.3.3 to 3.9.4.
- [Release notes](https://github.com/sidorares/node-mysql2/releases)
- [Changelog](https://github.com/sidorares/node-mysql2/blob/master/Changelog.md)
- [Commits](sidorares/node-mysql2@v2.3.3...v3.9.4)

---
updated-dependencies:
- dependency-name: mysql2
  dependency-type: direct:production
...

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

Author: dependabot[bot]

package-lock.json

@@ -31,7 +31,7 @@
     "express-rescue": "^1.1.31",
     "http-status-codes": "^2.2.0",
     "jsonwebtoken": "^8.5.1",
-    "mysql2": "^2.3.3",
+    "mysql2": "^3.9.4",
     "nodemon": "^2.0.19"
   }
 }