GHSA-35wc-cvqg-78fp

### Description

`IntlExtension` memoises every `\IntlDateFormatter` and `\NumberFormatter` it creates in instance-level arrays keyed on a hash that includes `locale`, `pattern`, `attrs` and other values that are ordinary named arguments of the `format_datetime` / `format_date` / `format_time` / `format_number` / `format_currency` filters. There is no size limit and no eviction.

A template that iterates over many distinct `pattern` (or `locale`, or `grouping_used`, ...) values therefore allocates one ICU formatter object per distinct value and pins it for the entire lifetime of the `Twig\Environment`. Because ICU allocates its backing buffers outside the Zend memory manager, this growth is not bounded by `memory_limit`. On long-running runtimes (RoadRunner, Swoole, FrankenPHP worker mode, ReactPHP) where the `Environment` outlives a single request, the cache also accumulates across requests.

### Resolution

The formatter caches are now bounded in size (100 entries each) and evict on a FIFO basis.

### Credits

Twig would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.