transpile <xsl:attribute name>

psr/cache to 3.0 (#39)

drop php 8.1/8.2, add 8.3

only support versions that are supported by PHP itself

add support for php 8.2 (#36)

* add support for php 8.2

php 8.1 compat (#34)

* more php 8.1 compat

* drop php 7.4

fix invalid current-grouping-key when called in new for-each

simplification of xsl:for-each-group

update supported versions

fix zero usage in sequence constructor