Bump clean-css from 4.2.2 to 4.2.3

Bumps [clean-css](https://github.com/jakubpawlowicz/clean-css) from 4.2.2 to 4.2.3.
- [Release notes](https://github.com/jakubpawlowicz/clean-css/releases)
- [Changelog](https://github.com/jakubpawlowicz/clean-css/blob/master/History.md)
- [Commits](https://github.com/jakubpawlowicz/clean-css/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

yarn.lock

@@ -1585,9 +1585,9 @@ class-utils@^0.3.5:
     static-extend "^0.1.1"
 
 clean-css@^4.1.9:
-  version "4.2.2"
-  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.2.2.tgz#8519abda724b3e759bc79d196369906925d81a3f"
-  integrity sha512-yKycArwReQXbOD/3pmsPmt6p7oUBww8MisDabL2pCUWkbVONvCJoBdCjgY4ZVQmKX5juz/JB9oDcP6XzGUpjwQ==
+  version "4.2.3"
+  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.2.3.tgz#507b5de7d97b48ee53d84adb0160ff6216380f78"
+  integrity sha512-VcMWDN54ZN/DS+g58HYL5/n4Zrqe8vHJpGA8KdgUXFU4fuP/aHNw8eld9SyEIyabIMJX/0RaY/fplOo5hYLSFA==
   dependencies:
     source-map "~0.6.0"