CI: Add initial GitHub Actions configuration

Fixes: #2569
(backported from commit d4cad0f)

.github/workflows/linux.yml

@@ -0,0 +1,14 @@
+name: Linux CI
+
+on: [push, pull_request]
+
+jobs:
+  build_and_test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Build the Fedora testing environment
+        run: docker build -t rpm -f ci/Dockerfile .
+      - name: Run the test suite
+        run: docker run -t rpm