Regex literal in Hurl files are not escaped when exported to HTML, allowing injections

Summary

Given this Hurl file: regex.hurl: ``` GET https://foo.com HTTP 200 [Asserts] jsonpath "$.body" matches /<img src="" onerror="alert('Hi!')">/ ``` When exported to HTML: ``` $ hurlfmt --out html regex.hurl <pre><code class="language-hurl"><span class="hurl-entry"><span class="request"><span class="line"><span class="method">GET</span> <span class="url">https://foo.com</span></span> </span><span class="response"><span class="line"><span class="version">HTTP</span> <span class="number">200</span></span> <span class="line"><span class="section-header">[Asserts]</span></span> <span class="line"><span class="query-type">jsonpath</span> <span class="string">"$.body"</span> <span class="predicate-type">matches</span> <span class="regex">/<img src="" onerror="alert('Hi!')">/</span></span> </span></span><span class="line"></span> </code></pre> ``` The regex literal `/<img src="" onerror="alert('Hi!')">/` is not escaped: `<span class="regex">/<img src="" onerror="alert('Hi!')">/</span></span>` When opened in a browser, the code is run without user interaction: