chore(deps): update dependency apple/swift-nio to v2.81.0 (#1479)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [apple/swift-nio](https://redirect.github.com/apple/swift-nio) | minor
| `2.80.0` -> `2.81.0` |

---

### Release Notes

<details>
<summary>apple/swift-nio (apple/swift-nio)</summary>

###
[`v2.81.0`](https://redirect.github.com/apple/swift-nio/releases/tag/2.81.0):
SwiftNIO 2.81.0

[Compare
Source](https://redirect.github.com/apple/swift-nio/compare/2.80.0...2.81.0)

<!-- Release notes generated using configuration in .github/release.yml
at main -->

#### What's Changed

##### SemVer Minor

- Make \_NIOFileSystem strict concurrency compatible by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3098](https://redirect.github.com/apple/swift-nio/pull/3098)
- Add ChannelPipeline.SynchronousOperations.Position by
[@&#8203;0xTim](https://redirect.github.com/0xTim) in
[https://github.com/apple/swift-nio/pull/3065](https://redirect.github.com/apple/swift-nio/pull/3065)

##### SemVer Patch

- Enable strict concurrency checking for NIOTLS by
[@&#8203;rnro](https://redirect.github.com/rnro) in
[https://github.com/apple/swift-nio/pull/3112](https://redirect.github.com/apple/swift-nio/pull/3112)

##### Other Changes

- Update the legacy CI matrix for 6.1 nightly by
[@&#8203;rnro](https://redirect.github.com/rnro) in
[https://github.com/apple/swift-nio/pull/3094](https://redirect.github.com/apple/swift-nio/pull/3094)
- Opt \_NIOConcurrency into Strict Concurrency by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3095](https://redirect.github.com/apple/swift-nio/pull/3095)
- Opt NIOFoundationCompat into strict concurrency by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3096](https://redirect.github.com/apple/swift-nio/pull/3096)
- Opt NIO module into Strict Concurrency by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3097](https://redirect.github.com/apple/swift-nio/pull/3097)
- Clean up concurrency in NIOEchoClient by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3099](https://redirect.github.com/apple/swift-nio/pull/3099)
- Add strict concurrency to NIOUDPEchoServer by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3101](https://redirect.github.com/apple/swift-nio/pull/3101)
- Lock in strict concurrency in NIOEchoServer by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3100](https://redirect.github.com/apple/swift-nio/pull/3100)
- Update NIOUDPEchoClient for strict concurrency by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3102](https://redirect.github.com/apple/swift-nio/pull/3102)
- Strict concurrency for TCP examples by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3103](https://redirect.github.com/apple/swift-nio/pull/3103)
- Strict concurrency for the chat examples by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3104](https://redirect.github.com/apple/swift-nio/pull/3104)
- Strict concurrency enablement for some test targets by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3105](https://redirect.github.com/apple/swift-nio/pull/3105)
- Strict concurrency for NIOTests by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3106](https://redirect.github.com/apple/swift-nio/pull/3106)
- Make the FileSystem world strict concurrency clean by
[@&#8203;Lukasa](https://redirect.github.com/Lukasa) in
[https://github.com/apple/swift-nio/pull/3107](https://redirect.github.com/apple/swift-nio/pull/3107)
- document known Structured Concurrency violations by
[@&#8203;weissi](https://redirect.github.com/weissi) in
[https://github.com/apple/swift-nio/pull/3108](https://redirect.github.com/apple/swift-nio/pull/3108)

**Full Changelog**:
apple/swift-nio@2.80.0...2.81.0

</details>

---

### Configuration

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

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR is behind base branch, or you tick the
rebase/retry checkbox.

👻 **Immortal**: This PR will be recreated if closed unmerged. Get
[config
help](https://redirect.github.com/renovatebot/renovate/discussions) if
that's undesired.

---

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

---

This PR has been generated by [Renovate
Bot](https://redirect.github.com/renovatebot/renovate).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzOC45NC4xIiwidXBkYXRlZEluVmVyIjoiMzguOTQuMSIsInRhcmdldEJyYW5jaCI6Im1haW4iLCJsYWJlbHMiOltdfQ==-->

Co-authored-by: cgrindel-self-hosted-renovate[bot] <139595543+cgrindel-self-hosted-renovate[bot]@users.noreply.github.com>

Author: cgrindel-self-hosted-renovate[bot]

examples/ios_sim/Package.swift

@@ -5,7 +5,7 @@ import PackageDescription
 let package = Package(
     name: "ios_sim",
     dependencies: [
-        .package(url: "https://github.com/apple/swift-nio.git", exact: "2.80.0"),
+        .package(url: "https://github.com/apple/swift-nio.git", exact: "2.81.0"),
         .package(url: "https://github.com/apple/swift-markdown.git", exact: "0.5.0"),
     ]
 )