Bump path-to-regexp and express in /react-express-mysql/backend

Bumps [path-to-regexp](https://github.com/pillarjs/path-to-regexp) to 0.1.12 and updates ancestor dependency [express](https://github.com/expressjs/express). These dependencies need to be updated together.


Updates `path-to-regexp` from 0.1.7 to 0.1.12
- [Release notes](https://github.com/pillarjs/path-to-regexp/releases)
- [Changelog](https://github.com/pillarjs/path-to-regexp/blob/master/History.md)
- [Commits](https://github.com/pillarjs/path-to-regexp/compare/v0.1.7...v0.1.12)

Updates `express` from 4.17.1 to 4.21.2
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/4.21.2/History.md)
- [Commits](https://github.com/expressjs/express/compare/4.17.1...4.21.2)

---
updated-dependencies:
- dependency-name: path-to-regexp
  dependency-version: 0.1.12
  dependency-type: indirect
- dependency-name: express
  dependency-version: 4.21.2
  dependency-type: direct:production
...

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

react-express-mysql/backend/package.json

@@ -14,7 +14,7 @@
     "test-wait-debuger": "cross-env NODE_ENV=test PORT=8081 mocha --no-timeouts --exit --inspect-brk=0.0.0.0:9230"
   },
   "dependencies": {
-    "express": "^4.17.1",
+    "express": "^4.21.2",
     "knex": "^0.95.11",
     "morgan": "^1.10.0",
     "mysql2": "^2.1.0"