Fix change log references

Author: vearutop

CHANGELOG.md

@@ -19,6 +19,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 - Export `null` value instead of skipping it for properties having `null` type.
 
-[0.12.22]: https://github.com/swaggest/php-code-builder/compare/v0.12.21...v0.12.22
-[0.12.21]: https://github.com/swaggest/php-code-builder/compare/v0.12.20...v0.12.21
-[0.12.20]: https://github.com/swaggest/php-code-builder/compare/v0.12.19...v0.12.20
+[0.12.22]: https://github.com/swaggest/php-json-schema/compare/v0.12.21...v0.12.22
+[0.12.21]: https://github.com/swaggest/php-json-schema/compare/v0.12.20...v0.12.21
+[0.12.20]: https://github.com/swaggest/php-json-schema/compare/v0.12.19...v0.12.20