Bump mysql2 from 2.2.5 to 3.9.4 in /frameworks/JavaScript/fastify

Bumps [mysql2](https://github.com/sidorares/node-mysql2) from 2.2.5 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](https://github.com/sidorares/node-mysql2/compare/v2.2.5...v3.9.4)

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

Signed-off-by: dependabot[bot] <[email protected]>

frameworks/JavaScript/fastify/package.json

@@ -10,7 +10,7 @@
     "handlebars": "4.7.6",
     "knex": "2.4.2",
     "mongodb": "3.5.9",
-    "mysql2": "2.2.5",
+    "mysql2": "3.9.4",
     "pg": "8.5.1"
   }
 }