CentOS 8 is EOL, and the official docker images will not be updated. See
https://www.centos.org/centos-linux-eol/
This switches to the latest release (CentOS 9 Stream). Since CentOS no
longer provides official images, this uses a third-party image provider
(https://hub.docker.com/u/tgagor)
This change also exposed a warning in absl that needed to be silenced in
the default version of GCC in CentOS 9 Stream (GCC 11.4).