fix(deps): update dependency require-in-the-middle to v6 (#1483)

[![Mend Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [require-in-the-middle](https://togithub.com/elastic/require-in-the-middle) | [`^5.0.0` -> `^6.0.0`](https://renovatebot.com/diffs/npm/require-in-the-middle/5.2.0/6.0.0) | [![age](https://badges.renovateapi.com/packages/npm/require-in-the-middle/6.0.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/npm/require-in-the-middle/6.0.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/npm/require-in-the-middle/6.0.0/compatibility-slim/5.2.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/npm/require-in-the-middle/6.0.0/confidence-slim/5.2.0)](https://docs.renovatebot.com/merge-confidence/) |

---

### Release Notes

<details>
<summary>elastic/require-in-the-middle</summary>

### [`v6.0.0`](https://togithub.com/elastic/require-in-the-middle/blob/HEAD/CHANGELOG.md#v600)

[Compare Source](https://togithub.com/elastic/require-in-the-middle/compare/v5.2.0...v6.0.0)

-   Drop Node.js 6 support. New minimum supported Node.js version is 8.6.0.
    (This is the minimum supported Node.js version for elastic-apm-node@3 that uses
    this module.)
-   Add testing of Node.js 19.
-   Rename default branch from `master` to `main`.
-   Should there be a need to do 5.x maintenance releases there is a
    [5.x branch](https://togithub.com/elastic/require-in-the-middle/tree/5.x).

</details>

---

### Configuration

📅 **Schedule**: Branch creation - "after 9am and before 3pm" (UTC), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR is behind base branch, 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 has been generated by [Mend Renovate](https://www.mend.io/free-developer-tools/renovate/). View repository job log [here](https://app.renovatebot.com/dashboard#github/googleapis/cloud-trace-nodejs).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNC43My4zIiwidXBkYXRlZEluVmVyIjoiMzQuNzMuMyJ9-->

package.json

@@ -101,7 +101,7 @@
     "hex2dec": "^1.0.1",
     "is": "^3.2.0",
     "methods": "^1.1.1",
-    "require-in-the-middle": "^5.0.0",
+    "require-in-the-middle": "^6.0.0",
     "semver": "^7.0.0",
     "shimmer": "^1.2.0",
     "source-map-support": "^0.5.16",