Update CHANGELOG.md

Author: oleibman

CHANGELOG.md

@@ -26,6 +26,9 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 ### Fixed
 
 - IF Empty Arguments. [Issue #3875](https://github.com/PHPOffice/PhpSpreadsheet/issues/3875) [Issue #2146](https://github.com/PHPOffice/PhpSpreadsheet/issues/2146) [PR #3879](https://github.com/PHPOffice/PhpSpreadsheet/pull/3879)
+- Changes to floating point in Php8.4. [Issue #3896](https://github.com/PHPOffice/PhpSpreadsheet/issues/3896) [PR #3897](https://github.com/PHPOffice/PhpSpreadsheet/pull/3897)
+- Handling User-supplied Decimal and Thousands Separators. [Issue #3900](https://github.com/PHPOffice/PhpSpreadsheet/issues/3900) [PR #3903](https://github.com/PHPOffice/PhpSpreadsheet/pull/3903)
+- Improve Performance of CSV Writer. [Issue #3904](https://github.com/PHPOffice/PhpSpreadsheet/issues/3904) [PR #3906](https://github.com/PHPOffice/PhpSpreadsheet/pull/3906)
 
 ## 2.0.0 - 2024-01-04