/dashboard/export API compatibility issue between v1.5 and v2.0

[xingyc15]

We have some dashboard developed in v1.5.0. After we upgrade the dashboard into v2.0.0, and use the /dashboard/export API endpoint to export the dashboards, there are unreadable characters in the exported json file.

How to reproduce the bug

1. Develop a dashboard under superset version 1.5.0
2. Upgrade superset to version 2.0.0
3. Use /dashboard/export API to export the dashboard into a json file
4. See error

Expected results

The dashboard json exported from v1.5.0 should be able to be successfully parsed by superset v2.0.0

Actual results

There are some unreadable characters.

The json file starts with this: PK!�gٝMM.dashboard_export_20220806T005733/metadata.yamlversion: 1.0.0 type: Dashboard timestamp: '2022-08-06T00:57:33.133934+00:00' PK!?�8���Fdashboard_export_20220806T005733/datasets/pinot/map_labeling_logs.yamltable_name: map_labeling_logs ...

Environment

• superset version: 1.5.0 and 2.0.0

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• [x] I have checked the superset logs for python stacktraces and included it here as text if there are any.
• [x] I have reproduced the issue with at least the latest released version of superset.
• [x] I have checked the issue tracker for the same issue and I haven't found one similar.