chore: update CHANGELOG.md for v12.4.1

Author: shawnbot

CHANGELOG.md

@@ -1,3 +1,25 @@
+# 12.4.1
+
+### :bug: Bug fixes
+- Fix [#822](https://github.com/primer/css/issues/822) (`.border-dashed` issues) via [#824](https://github.com/primer/css/issues/824)
+
+### :memo: Documentation
+- Typos fixed in [#802](https://github.com/primer/css/issues/802) (thank you, [@The-Compiler](https://github.com/The-Compiler)!)
+- Nav updates [#803](https://github.com/primer/css/issues/803)
+- Fix tables of contents [#762](https://github.com/primer/css/issues/762)
+- Add deprecation warning for `.btn-purple`, due to disappear in 13.0.0 via [#736](https://github.com/primer/css/issues/736)
+- Lots more documentation updates in [#814](https://github.com/primer/css/issues/814)
+
+### :house: Internal
+- Decommission `primer/deploy` [#809](https://github.com/primer/css/issues/809)
+
+### Committers
+- [@emplums](https://github.com/emplums)
+- [@shawnbot](https://github.com/shawnbot)
+- [@simurai](https://github.com/simurai)
+- [@The-Compiler](https://github.com/The-Compiler)
+
+
 # 12.4.0
 
 ### :rocket: Enhancement