snap: build a devmode test snap (in ci)

.github/workflows/ci.yml

@@ -49,3 +49,14 @@ jobs:
       env:
         RUST_LOG: debug
       run: timeout 30m cargo test -- --nocapture
+
+  snap:
+    needs: build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: snapcore/action-build@v1
+      - uses: actions/upload-artifact@v3
+        with:
+          name: snap
+          path: ${{ steps.snapcraft.outputs.snap }}