meta: add nodejs/test_runner to CODEOWNERS

PR-URL: https://github.com/nodejs/node/pull/45935
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>

.github/CODEOWNERS

@@ -120,3 +120,12 @@
 
 /.github/workflows/* @nodejs/actions
 /tools/actions/* @nodejs/actions
+
+# Test runner
+
+/test/message/test_runner_* @nodejs/test_runner
+/test/parallel/test-runner-* @nodejs/test_runner
+/doc/api/test.md @nodejs/test_runner
+/lib/test.js @nodejs/test_runner
+/lib/internal/main/test_runner.js @nodejs/test_runner
+/lib/internal/test_runner/* @nodejs/test_runner