Remove indentation for bullet list

This commit removes the unnecessary indentation of the bullet list in
the releasenote. It causes weird rendering on the web page.

 https://docs.openstack.org/releasenotes/tempest/unreleased.html#relnotes-23-0-0

Change-Id: I146a9c8a74227aa1810e0a02d7cb6a91fbe4da08
1 file changed