v5.9.0

What's Changed

Inline some information that previously lived at the category level by @iainmcampbell in https://github.com/Shopify/liquid/pull/1968
Fix a typo in the documentation by @juharris in https://github.com/Shopify/liquid/pull/1952
Update documentation for loop's named parameters by @aswamy in https://github.com/Shopify/liquid/pull/1984
Avoid creating new regex objects in utility functions by @ggmichaelgo in https://github.com/Shopify/liquid/pull/1995
Introduce the :rigid parsing mode by @charlespwd @karreiro in https://github.com/Shopify/liquid/pull/1991

@iainmcampbell made their first contribution in https://github.com/Shopify/liquid/pull/1968
@juharris made their first contribution in https://github.com/Shopify/liquid/pull/1952
@aswamy made their first contribution in https://github.com/Shopify/liquid/pull/1984

Full Changelog: https://github.com/Shopify/liquid/compare/v5.8.7...v5.9.0