ci_fetch_deps: fetch lib/mp3 and extmod/ulab for zephyr-cp

zephyr-cp builds audiomp3 and ulab, but its PORT_DEPS left out both
submodules. Board builds only worked when the scheduler job's
submodules-common cache restored; with a cold cache they fail on
lib/mp3/src/mp3common.h.

Fixes #11655

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: tyeth

tools/ci_fetch_deps.py

@@ -96,7 +96,9 @@ def _all_submodules():
         "data/nvm.toml/",
     ],
     "zephyr-cp": [
+        "extmod/ulab/",
         "lib/certificates/",
+        "lib/mp3/",
         "lib/tinyusb/",
         "lib/tlsf",
     ],