A pile of CI updates

[timwoj]

• Remove EOL'd ubuntu 18.04, fedora 36, and opensuse-leap 15.3 builds
• Add fedora 38 build
• Update freebsd 13 build to 13.2
• Install python 3.8 on opensuse-leap 15.4, centos 7, and centos-stream-8 images
• Make the opensuse-tumbleweed build a rolling canary build for Linux, similar to how Zeek's builds work

[ckreibich]

Thanks Tim. We could use these refreshes for several repos and possibly release branches ... are you planning to do a sweep? We can divide and conquer, just ping me if I can help.

[timwoj]

Are you planning to do a sweep? We can divide and conquer, just ping me if I can help.

I wasn't. I was just doing updates as part of zeek/zeek#3239, and the rest of this seemed like low-hanging fruit.