Refresh composer.lock with new dependency (#134)

Author: vearutop

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.12.39] - 2021-10-16
+
+### Added
+- Polyfill dependency for mbstring extension.
+
 ## [0.12.38] - 2021-09-17
 
 ### Fixed
@@ -106,6 +111,7 @@ 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.
 
+[0.12.39]: https://github.com/swaggest/php-json-schema/compare/v0.12.38...v0.12.39
 [0.12.38]: https://github.com/swaggest/php-json-schema/compare/v0.12.37...v0.12.38
 [0.12.37]: https://github.com/swaggest/php-json-schema/compare/v0.12.36...v0.12.37
 [0.12.36]: https://github.com/swaggest/php-json-schema/compare/v0.12.35...v0.12.36