chore(ci): install restic in test env

.github/workflows/ci.yml

@@ -4,11 +4,25 @@ on:
   push:
     branches: [master]
 
+env: 
+  RESTIC_VERSION: "0.17.1"
+
 jobs:
   test:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+
+      - name: Install restic@${{ env.RESTIC_VERSION }}
+        run: |
+          mkdir -p tools/restic
+          curl --fail --location --silent --show-error --output tools/restic/restic.bz2 \
+            "https://github.com/restic/restic/releases/download/v${RESTIC_VERSION}/restic_${RESTIC_VERSION}_linux_amd64.bz2"
+          bzip2 -d tools/restic/restic.bz2
+          chmod +x tools/restic/restic
+          echo "$GITHUB_WORKSPACE/tools/restic" >> "$GITHUB_PATH"
+      - run: restic version
+
       - uses: actions/setup-go@v3
         with:
           go-version: '^1.21'