.github/workflows: add tools test action

Only compile_and_test_for_board is tested for the moment

.github/workflows/tools-test.yml

@@ -0,0 +1,31 @@
+name: tools-test
+
+on:
+  push:
+    branches:
+      - master
+    tags:
+      - '*'
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  python-tests:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.8
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install tox
+    - name: Test backport_pr
+      run: cd dist/tools/backport_pr && tox
+    - name: Test compile_and_test_for_board
+      run: cd dist/tools/compile_and_test_for_board && tox
+    - name: Test riotctrl_shell
+      run: cd dist/pythonlibs/riotctrl_shell && tox