cubicweb-timeseries #2200660 incompatibility with cw 3.15 [resolved]

cw 3.15 runs hooks on postcreate, so timeseries' own postcreate script is redundant and causes ExcelPreferences to be created twice.

prioritynormal
typebug
done in1.3.0
load0.100
load left0.000
closed by#1d4f5f4b9aa1 Fix for cubicweb 3.15 compat (closes #2200660)