Deprecation: #63974 - Deprecate CSS compressor callback method

See Issue #63974

Description

The callback method compressCssPregCallback() as defined in EXT:core/Classes/Resource/ResourceCompressor.php has been marked as deprecated due to the overhauled regular expressions.

Impact

Usage of the mentioned method is discouraged and will break as of CMS 8.

Affected installations

All installations or extensions using the compressCssPregCallback() callback method.

Migration

No migration possible for the callback method.