Possible ReDoS vulnerability in plain_text_for_blockquote_node in Action Text

Action Text brings rich text content and editing to Rails. Starting in version 6.0.0 and prior to versions 6.1.7.9, 7.0.8.5, 7.1.4.1, and 7.2.1.1, there is a possible ReDoS vulnerability in the `plain_text_for_blockquote_node helper` in Action Text. Carefully crafted text can cause the `plain_text_for_blockquote_node` helper to take an unexpected amount of time, possibly resulting in a DoS vulnerability. All users running an affected release should either upgrade to versions 6.1.7.9, 7.0.8.5, 7.1.4.1, or 7.2.1.1 or apply the relevant patch immediately. As a workaround, users can avoid calling `plain_text_for_blockquote_node` or upgrade to Ruby 3.2. Ruby 3.2 has mitigations for this problem, so Rails applications using Ruby 3.2 or newer are unaffected. Rails 8.0.0.beta1 depends on Ruby 3.2 or greater so is unaffected.