**Information** - Language: Ruby <!-- Please verify that the problem still occurs in the latest version of Prism. You can check this using the [test page](https://prismjs.com/test.html) or by getting the latest version at our [download page](https://prismjs.com/download.html). --> **Description** Ruby has a lot of regex flags but Prism only supports `i`, `m`, and `g`. **Code snippet** [Test page](https://prismjs.com/test.html#language=ruby&text=%2Fabc%2Fu) <details> <summary>The code being highlighted incorrectly.</summary> ``` /abc/u ``` </details>