actions: manifest: Remove unnecessary west update command

In commit f7eb8c8, we introduced the use of the use-tree-checkout
option. But at the same time we also restricted the parsed imports to
self:, which means that the import statement for sdk-zephyr in the main
west.yml file in sdk-nrf is ignored when running this action. Hence,
there's no need to actually clone the zephyr tree as part of the action
execution.

Signed-off-by: Carles Cufi <[email protected]>

Author: carlescufi

.github/workflows/manifest.yml

@@ -27,8 +27,6 @@ jobs:
           git config --global user.email "[email protected]"
           git config --global user.name "Your Name"
           west init -l . || true
-          # We only import the zephyr manifest
-          west update zephyr
 
       - name: Manifest
         uses: zephyrproject-rtos/action-manifest@ea38f222cddfbbb9debb5f0239f4139ae2677ebb # v1.8.0