Release v1.3 tasks

[aofei]

Release PR: #581

Pre-release

1. Add a new column files_hash to the asset DB table. (See Add duplicate asset check when adding to library #549)

Post-release

1. Manually update all URLs in the files column of the project and asset tables from https://builder-static.goplus.org/... to kodo://goplus-builder-static/.... (See Switch downloading Kodo objects from unsigned to signed URLs #497 and spx-backend: store only object keys, not full URLs in the database #411)
2. Once the above changes are complete and verified, make the Kodo bucket goplus-builder-static private.

[aofei]

done