Set pypi_twine_executable for upload-pypi role
Set pypi_twine_executable for upload-pypi role

Use the full path for twine to avoid pathing issues.

Change-Id: Ie4b500bea8fcf48092cee29c58ae5c05e28cfff4
Depends-On: I5c757b29e185ab76495abf3cfb2d853aada77a50
Signed-off-by: Paul Belanger <e7139c8e6c4ea75cc1c287ce081b2dc0f3ab39ec@redhat.com>

openstack-infra/project-config,openstack-infra/project-config