Missing CSS files in static/appbuilder/ after upgrade from 3.0.1 to 3.0.2

[maxgillmaxgill]

I installed Superset 3.0.1 from scratch and everything worked fine. I upgraded Superset to 3.0.2 and now I am getting 3 missing CSS files in the browser console

How to reproduce the bug

1. Install Superset 3.0.1
2. Upgrade it to 3.0.2
3. Open Superset from the browser and open Chrome's console

Expected results

No errors

Actual results

Missing the following files:
https://superset.someDomain.com:8089/static/appbuilder/select2/select2.css net::ERR_ABORTED 404 (NOT FOUND)
https://superset.someDomain.com:8089/static/appbuilder/datepicker/bootstrap-datepicker.css net::ERR_ABORTED 404 (NOT FOUND)
https://superset.someDomain.com:8089/static/appbuilder/select2/select2-bootstrap-theme.css net::ERR_ABORTED 404 (NOT FOUND)

Screenshots

Environment

(please complete the following information):

• browser type and version: Chjrome latest stable
• superset version: 3.0.2
• python version: 3.9
• node.js version: latest stable
• any feature flags active: nothing special

Checklist

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

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

Additional context

Add any other context about the problem here.