[qa] Proposing Sean and Tosky to Devstack core

Hello Everyone, I would like to propose adding sean-k-mooney and tosky to Devstack core team. Both have shown great knowledge and have been engaged with Devstack for a long time. Having them in the core group would help us to continue maintaining Devstack. Feel free to provide your thoughts. If there are no objections by next week, I plan to add them to the Gerrit group by Friday, August 8th. -gmaan