As of PHP ~v8 the zip_open and associated functions have been deprecated and
removed. The replacement is the ZipArchive API. This updates the figlet
implementation to use this API which has been present in PHP since 5.2.
Additionally in PHP 8 the use of squiggly brackets for indexing into arrays
is also deprecated. This updates to remove two uses of squiggly brackets and
replace with square brackets.
These two deprecations would result in being unable to load differential
revisions in which someone had commented using figlet remarkup.