Add ulab to included modules

This change submodules in our fork of ulab with an added usermod.cmake and adds it to the top-level usermod.cmake for our shipped modules.

It should - in theory - result in ulab being included in release builds.

.github/workflows/micropython.yml

@@ -36,6 +36,7 @@ jobs:
 
     - uses: actions/checkout@v2
       with:
+        submodules: true
         path: pimoroni-pico
 
     # Linux deps

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "micropython/modules/ulab"]
+	path = micropython/modules/ulab
+	url = https://github.com/pimoroni/micropython-ulab.git

micropython/modules/ulab

@@ -0,0 +1 @@
+Subproject commit 486bab167c37f94fbc313c45451064710f669df2

micropython/modules/usermod.cmake

@@ -3,3 +3,4 @@ include(${CMAKE_CURRENT_LIST_DIR}/pico_rgb_keypad/usermod.cmake)
 include(${CMAKE_CURRENT_LIST_DIR}/pico_unicorn/usermod.cmake)
 include(${CMAKE_CURRENT_LIST_DIR}/pico_display/usermod.cmake)
 include(${CMAKE_CURRENT_LIST_DIR}/pico_explorer/usermod.cmake)
+include(${CMAKE_CURRENT_LIST_DIR}/ulab/code/usermod.cmake)