Added CI

.github/workflows/backup.sh.yml

@@ -0,0 +1,22 @@
+name: backup.sh
+on:
+  push:
+    branches: [master]
+  workflow_dispatch:
+
+jobs:
+  bash:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install dependencies
+        run: |
+          apt update
+          apt -y install rsync tar openssl shellcheck
+      - name: Run ShellCheck
+        run: |
+          shellcheck backup.sh
+          shellcheck tests.sh
+      - name: Run unit tests
+        run: |
+          ./tests.sh I_HAVE_READ_THE_HELPER