Auto update change indication by github actions

Co-authored-by: kamilritz <kamilritz@users.noreply.github.com>

.github/workflows/functional_change_indicator.yml

@@ -1,21 +1,19 @@
 name: Change Indicator
 
-on:
-  push:
-    branches:
-      - master
-  pull_request:
-    branches:
-      - '*'
+on: pull_request
 
 jobs:
   unit_tests:
     runs-on: ubuntu-latest
     container: px4io/px4-dev-base-focal:2020-09-14
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.1
+    - name: checkout newest version of branch
+      run: |
+        git fetch origin pull/${{github.event.pull_request.number}}/head:${{github.head_ref}}
+        git checkout ${GITHUB_HEAD_REF}
     - name: main test
       run: make test
-    - name: Check if there exists diff
-      run: git diff --exit-code
+    - name: Check if there is a functional change
+      run:  git diff --exit-code
       working-directory: test/change_indication