[election][barbican] Add Douglas Mendizábal candidacy for Barbican PTL

Hello OpenStack, I would like to nominate myself for Barbican PTL. [1] My focus for the new cycle will be to continue the maintenance and development of the project. We will continue to improve usability as well as continue to enable cross-project encryption features. We hope to deliver our first microversion revision early in the Wallaby cycle, so tha we can finally release the Secret Consumers feature. Thanks, Douglas Mendizábal [1] https://review.opendev.org/#/c/754735/