Update Alpine Linux Synapse Package Maintainer within installation.md (#17846)

Update Alpine Linux Synapse Package Maintainer within installation.md as
it is outdated.

### Pull Request Checklist

<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->

* [x] Pull request is based on the develop branch
* [N/A] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
  - Use markdown where necessary, mostly for `code blocks`.
  - End with either a period (.) or an exclamation mark (!).
  - Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [x] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct
(run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))

changelog.d/17846.misc

@@ -0,0 +1 @@
+Update Alpine Linux Synapse Package Maintainer within installation.md.

docs/setup/installation.md

@@ -157,7 +157,7 @@ sudo pip install py-bcrypt
 
 #### Alpine Linux
 
-6543 maintains [Synapse packages for Alpine Linux](https://pkgs.alpinelinux.org/packages?name=synapse&branch=edge) in the community repository. Install with:
+Jahway603 maintains [Synapse packages for Alpine Linux](https://pkgs.alpinelinux.org/packages?name=synapse&branch=edge) in the community repository. Install with:
 
 ```sh
 sudo apk add synapse