Use Zephyr GitHub action for CI

.github/workflows/build.yml

@@ -5,31 +5,28 @@ on: [push, pull_request]
 jobs:
   build:
     runs-on: ubuntu-latest
-    container: zephyrprojectrtos/ci:latest
-    env:
-      CMAKE_PREFIX_PATH: /opt/toolchains
     steps:
       - name: Checkout
         uses: actions/checkout@v3
         with:
           path: thingset-node-c
           fetch-depth: 0 # necessary to get tags
 
+      - name: Setup Zephyr project
+        uses: zephyrproject-rtos/action-zephyr-setup@v1
+        with:
+          app-path: thingset-node-c
+
       - name: Trailing whitespace check
         working-directory: thingset-node-c
         run: |
           git diff --check `git rev-list HEAD | tail -n 1`..
 
-      - name: Initialize west workspace
-        working-directory: thingset-node-c
-        run: |
-          west init -l .
-          west update
-
       - name: Install docs dependencies
         working-directory: thingset-node-c
         run: |
-          sudo apt install -y git make python3 python3-pip doxygen
+          sudo apt-get update
+          sudo apt-get install -y doxygen lcov
           pip3 install -r docs/requirements.txt
 
       - name: Run unit tests
@@ -40,8 +37,6 @@ jobs:
       - name: Generate coverage report
         working-directory: thingset-node-c
         run: |
-          apt-get update
-          apt-get install lcov
           west build -b native_posix tests/protocol -t run
           lcov --capture --directory build/modules/thingset-node-c --output-file build/lcov.info --rc lcov_branch_coverage=1 --exclude '*zephyr*' --exclude '*lib*'
           genhtml build/lcov.info --output-directory build/lcov_html --ignore-errors source --branch-coverage --highlight --legend