Bump mysql2 from 3.9.3 to 3.9.4 in /GymNest-IS/booking-service

Bumps [mysql2](https://github.com/sidorares/node-mysql2) from 3.9.3 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@v3.9.3...v3.9.4)

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

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

GymNest-IS/booking-service/package.json

@@ -15,7 +15,7 @@
     "http-errors": "~2.0.0",
     "morgan": "~1.10.0",
     "pug": "~3.0.2",
-    "mysql2": "~3.9.3",
+    "mysql2": "~3.9.4",
     "swagger-jsdoc": "~6.2.8",
     "swagger-ui-express": "~5.0.0",
     "swagger-ui-dist": "~5.15.2"