mongodb: 1.21.4

2026-01-28T00:00:00+00:00

## What's Changed
* PHPC-2661: Use php-windows-builder for Windows extension builds by @alcaeus in https://github.com/mongodb/mongo-php-driver/pull/1907
* Refactor release process to support php-windows-builder by @alcaeus in https://github.com/mongodb/mongo-php-driver/pull/1916
* Fix broken release workflow by @alcaeus in https://github.com/mongodb/mongo-php-driver/pull/1919

**Full Changelog**: https://github.com/mongodb/mongo-php-driver/compare/1.21.2...1.21.4