Improvements 🔧

Support for some features from PHP 8.1
- Support for new in initializers - RFC (phpstan/phpstan-src@1a102fe)
- Support for first-class callables - RFC
- Support for array_is_list() - RFC (#770), thanks @canvural!
Support literal-string with encapsed strings (#768), thanks @craigfrancis!
Tips for always used properties and constants extensions (phpstan/phpstan-src@2db3c26)
Autowire rules from the rules config section by their class name (phpstan/phpstan-src@50cb90d)

Bugfixes 🐛

Type system: ConstantStringType created from ::class is always considered a classname (phpstan/phpstan-src@da34d3f), #5979
Do not run PHP bug workaround on PHP 8+ where it's fixed (phpstan/phpstan-src@6573959), #5954
Promoted properties do not have a default value (phpstan/phpstan-src@7c8e81d), #5906
CleaningParser - do not remove inline @var tags (phpstan/phpstan-src@2652f2d), #5921
AttributesCheck - do not report named arguments in attributes (phpstan/phpstan-src@6366066), #5898

functionMap - removed functions that are reserved keywords and separate AST nodes (phpstan/phpstan-src@08f3e2d), #6014