Pin oslo.serialization upper version
Pin oslo.serialization upper version

We use oslo.serialization that still uses namespaced package so we need it
in such version.

Change-Id: I914e1beedde8234c582f06fa77962095dd68058c
Closes-Bug: #1472250

eayunstack/fuel-ostf,stackforge/fuel-ostf,stackforge/fuel-ostf,eayunstack/fuel-ostf