chore: automatically run regression tests on pull request

.github/workflows/tests.yml

@@ -0,0 +1,21 @@
+name: C/C++ CI
+
+on: [pull_request]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: install prerequisites
+      run: sudo apt update && sudo apt install -y libgtk2.0-dev libglib2.0-dev
+    - name: configure
+      run: ./configure
+    - name: make
+      run: make
+    - name: check executability
+      run: ./dvdisaster --version
+    - name: regression tests
+      run: mkdir /var/tmp/regtest && ./regtest/runtests.sh