Replace Travis CI with GitHub actions (#939)

* Test build images using github actions

Signed-off-by: Tilo Spannagel <development@tilosp.de>

* Check for Changes by update.sh using github actions

Signed-off-by: Tilo Spannagel <development@tilosp.de>

* Remove travis.yml

Signed-off-by: Tilo Spannagel <development@tilosp.de>

.github/workflows/update-sh.yml

@@ -0,0 +1,22 @@
+name: update.sh
+
+on:
+  pull_request:
+
+defaults:
+  run:
+    shell: 'bash -Eeuo pipefail -x {0}'
+
+jobs:
+
+  check-changes:
+    name: Check for Changes
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Check for Changes
+        run: |
+          hash_before="$(git write-tree)"
+          ./update.sh
+          git add -A
+          [[ "$hash_before" = "$(git write-tree)" ]]