cubicweb-task #2709165 upgrade to cw 3.16 [validation pending]

silence warnings from cw 3.16

prioritynormal
typetask
done in1.8.0
load0.100
load left0.000
closed by#5976637da4fc silence warnings from cubicweb 3.16 (closes #2709165)
patchsilence warnings from cubicweb 3.16 (closes #2709165) [applied]