[charms] Nominate Brian Haley for charms-stable-maint

I would like to nominate Brian Haley for charms-stable-maint. Brian has a long history of contributions to OpenStack, is the currentl PTL for the Neutron project, and over the past year, Brian has also been contributing to charm reviews [1]. I have no doubt that Brian will continue providing quality reviews to the OpenStack charms project and will be a great asset in helping the project move forward. [1] https://review.opendev.org/q/reviewer:haleyb.dev%2540gmail.com+project:%255E... Thanks, Corey