try to fix js tests

Author: samuelcolvin

tests/emscripten_runner.js

@@ -86,7 +86,7 @@ async function main() {
     FS.mkdir('/test_dir');
     FS.mount(FS.filesystems.NODEFS, {root: path.join(root_dir, 'tests')}, '/test_dir');
     FS.chdir('/test_dir');
-    await pyodide.loadPackage(['micropip', 'pytest']);
+    await pyodide.loadPackage(['micropip', 'pytest', 'pygments']);
     // language=python
     errcode = await pyodide.runPythonAsync(`
 import micropip