Update oslo-config version.

Update the version of oslo-config in pip-requires.  This update includes
a fix for a bug that breaks oslo.config imports.

Change-Id: I2e31d3980c495b1fd16db5488c7d3c982ce069ac
Removed redundant assertion

Change-Id: Iba9f0a5bd713b21487471eb64ce931910b1ca912
Merge "Removed redundant assertion"
Merge "Update oslo-config version."