Auto merge of #26791 - camelid:patch-1, r=jdm

Replace IRC link with Matrix

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Replace the IRC link in `CONTRIBUTING.md` with a link to the Matrix room.

Same as servo/servo-starters#55.

---
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- [ ] `./mach build -d` does not report any errors (only a docs change)
- [ ] `./mach test-tidy` does not report any errors (only a docs change)
- [ ] These changes fix #___ (GitHub issue number if applicable)

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because this is only a docs change

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CONTRIBUTING.md

@@ -51,6 +51,6 @@ In all Servo-related forums, we follow the [Rust Code of Conduct](https://www.ru
 
 ## Communication
 
-Servo contributors frequent the `#servo` channel on [`irc.mozilla.org`](https://wiki.mozilla.org/IRC).
+Servo contributors frequent the [Servo room](https://chat.mozilla.org/#/room/#servo:mozilla.org) on [Mozilla Matrix](https://wiki.mozilla.org/Matrix).
 
 You can also join the [`dev-servo` mailing list](https://lists.mozilla.org/listinfo/dev-servo).