Fix Percy/Puppeteer sandbox error in GitHub Actions

Added --no-sandbox and --disable-setuid-sandbox flags to Puppeteer
launch options to fix the browser launch failure in GitHub Actions.

The error was caused by Ubuntu 23.10+ disabling unprivileged user
namespaces with AppArmor, preventing Chromium's sandbox from working
in containerized CI environments.

These flags are standard practice for running headless Chrome in CI/CD
pipelines and are recommended by the Puppeteer troubleshooting guide.

Author: DarkMatterMatt

packages/web/test/snapshot.mjs

@@ -55,7 +55,9 @@ async function main(args) {
         .listen(8080);
 
     // launch puppeteer
-    const browser = await launch();
+    const browser = await launch({
+        args: ['--no-sandbox', '--disable-setuid-sandbox'],
+    });
     const page = await browser.newPage();
 
     // wait for a marker to appear