The license of the Poll is not applied after upgrade

[ane-gabriela]

Steps to reproduce:

1. Install an older version of Poll App eg. V 1.10.9
2. Get a trial license
3. Create a Poll
4. Upgrade the Poll to V 2.0

Expected results: The Poll works normal after the upgrade.

Actual results: A zip file closed warning appears in the Progress log, an error message in the XWiki console and the message that No valid license exists.
After clicking on the "Check for Updates" button the license appears again.

Environment: Windows 10, XWiki 11.8.1 with MySQL 5.7 and Chrome 78

Note: It appears to be similar to #77

[mflorea]

Same as xwikisas/application-diagram#77 . It looks more like a platform issue (with the Extension Manager). @tmortagne tried to investigate, but I don't know if he found something.