actions: manifest: Align with upstream Zephyr

The manifest action now has many more features at version 1.6.0. Update
to the latest and start using a tree checkout to diff the manifest,
which is compatible with split manifests.

This is a second attempt after bf6df10
had to be reverted in f4744e2 due to
the fact that the actual action did not support selecting which projects
to import. This has now been fixed in:
zephyrproject-rtos/action-manifest@1807b4c
and included in v1.6.0 of the action.

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

.github/workflows/manifest.yml

@@ -1,14 +1,12 @@
 name: Manifest
-
-on:
-  pull_request_target:
+on: pull_request_target
 
 permissions:
   contents: read
   pull-requests: write
 
 jobs:
-  contribs:
+  manifest:
     runs-on: ubuntu-latest
     name: Manifest
     steps:
@@ -20,19 +18,28 @@ jobs:
           fetch-depth: 0
           persist-credentials: false
 
+      - name: west setup
+        env:
+          BASE_REF: ${{ github.base_ref }}
+        working-directory: ncs/nrf
+        run: |
+          pip3 install west
+          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@16c4cfa380ae2b6fa3daddb1a35032e69422a20f
+        uses: zephyrproject-rtos/action-manifest@v1.6.0
         with:
           github-token: ${{ secrets.NCS_GITHUB_TOKEN }}
           manifest-path: 'west.yml'
           checkout-path: 'ncs/nrf'
+          use-tree-checkout: 'true'
+          west-import-flag: 'self'
+          check-impostor-commits: 'true'
           label-prefix: 'manifest-'
           verbosity-level: '1'
-
-          # Add one label per line. 'manifest' always adds the label 'manifest'.
-          # 'CI-all-test:zephyr;nrfxlib,' adds the 'CI-all-test' label when the
-          # zephyr module or the nrfxlib module is changed. Each line is comma-
-          # separated.
-          labels: >
-            manifest
+          labels: 'manifest'
           dnm-labels: 'DNM'