CHANGELOG: Add v5.4.3 release (rails#3162)

Fix some compare links

CHANGELOG.md

@@ -2,7 +2,11 @@
 
 **Please note that Webpacker 4.1.0 has an installer bug. Please use 4.2.0 or above**
 
-## [[5.4.2]](https://github.com/rails/webpacker/compare/v5.4.0...v5.4.1) - 2021-08-20
+## [[5.4.3]](https://github.com/rails/webpacker/compare/v5.4.2...v5.4.3) - 2021-09-14
+
+-  Specify webpack-dev-server to be v3, to avoid getting webpack-dev-server v4 (#3121)
+
+## [[5.4.2]](https://github.com/rails/webpacker/compare/v5.4.1...v5.4.2) - 2021-08-20
 
 - Fix babel warning about private-methods in @babel/plugin-proposal-private-property-in-object as well.