Update dependency express to v4.21.1 (#996)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [express](http://expressjs.com/)
([source](https://redirect.github.com/expressjs/express)) | [`4.21.0` ->
`4.21.1`](https://renovatebot.com/diffs/npm/express/4.21.0/4.21.1) |
[![age](https://developer.mend.io/api/mc/badges/age/npm/express/4.21.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/npm/express/4.21.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/npm/express/4.21.0/4.21.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/express/4.21.0/4.21.1?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>expressjs/express (express)</summary>

###
[`v4.21.1`](https://redirect.github.com/expressjs/express/compare/4.21.0...8e229f92752ad51462c868b99f6e6c2e559801b0)

[Compare
Source](https://redirect.github.com/expressjs/express/compare/4.21.0...4.21.1)

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined),
Automerge - At any time (no schedule defined).

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR was generated by [Mend Renovate](https://mend.io/renovate/).
View the [repository job
log](https://developer.mend.io/github/line/line-bot-sdk-nodejs).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzOC45Ny4wIiwidXBkYXRlZEluVmVyIjoiMzguOTcuMCIsInRhcmdldEJyYW5jaCI6Im1hc3RlciIsImxhYmVscyI6WyJkZXBlbmRlbmN5IHVwZ3JhZGUiXX0=-->

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

package.json

@@ -69,7 +69,7 @@
     "@types/finalhandler": "1.2.3",
     "@types/mocha": "10.0.9",
     "@vitest/coverage-v8": "^2.0.0",
-    "express": "4.21.0",
+    "express": "4.21.1",
     "finalhandler": "1.3.1",
     "husky": "9.1.6",
     "msw": "2.4.9",