Remove hardcoded version.
Remove hardcoded version.

We use semantic versioning, not pbr's pre-version facility. This
line causes local package builds to have the wrong version, and
pbr will in future detect this and error.

Change-Id: If7972d9868122202003ea9ce5ada0ea9ab1a866c

varunarya10/diskimage-builder,switch-ch/diskimage-builder,NaohiroTamura/diskimage-builder,eantyshev/diskimage-builder,openstack/diskimage-builder,rdo-management/diskimage-builder,eantyshev/diskimage-builder,varunarya10/diskimage-builder,zioproto/diskimage-builder,rdo-management/diskimage-builder,NaohiroTamura/diskimage-builder,takahashinobuyuki/diskimage-builder,zioproto/diskimage-builder,CSC-IT-Center-for-Science/diskimage-builder,openstack/diskimage-builder,JioCloud/diskimage-builder,CSC-IT-Center-for-Science/diskimage-builder,takahashinobuyuki/diskimage-builder,switch-ch/diskimage-builder,JioCloud/diskimage-builder