actions: manifest: Update to the latest version

See these PRs for additional information on what changed between v1.5.0
and v1.7.0:

https://github.com/zephyrproject-rtos/action-manifest/pull/15
https://github.com/zephyrproject-rtos/action-manifest/pull/16

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

.github/workflows/manifest.yml

@@ -26,7 +26,7 @@ jobs:
           west init -l . || true
 
       - name: Manifest
-        uses: zephyrproject-rtos/action-manifest@v1.5.0
+        uses: zephyrproject-rtos/action-manifest@v1.7.0
         with:
           github-token: ${{ secrets.ZB_GITHUB_TOKEN }}
           manifest-path: 'west.yml'