update ynh version after #150 fix

[xoddark]

150: set app as owner of log folder in install/restore/update script

Problem

• the fix #150 is applied if update to 1.20.0~ynh1 was done before integration of the fix

Solution

• Update ynh version to '1.20.0~ynh2' to be sure the fix is applied for all

PR Status

• [X] Code finished and ready to be reviewed/tested
• [ ] The fix/enhancement were manually tested (if applicable)

[ericgaspar]

superseded by #155