Move 'AMD64 FreeBSD Refleaks' builds to FreeBSD14

[zware]

FreeBSD 13 is now EoL, so I'm working towards retiring my ware-freebsd worker.

@opsec, are you okay with this change moving the FreeBSD Refleaks builder to your FreeBSD 14 worker?

[vstinner]

Why not adding Refleaks jobs to FreeBSD 15? FreeBSD 15 is now ready for production: https://www.freebsd.org/. FreeBSD 14 is the previous version.

[zware]

I'm fine with either, mostly just went with 14 due to proximity :). We are probably due to bump 15 up to stable, though.

[vstinner]

We are probably due to bump 15 up to stable, though.

The FreeBSD15 buildbot is green for at least 3 weeks, so I'm fine with promoting it to stable: https://buildbot.python.org/#/builders/1238

[opsec]

The 15bot is running a not that recent version of 15. I had plans to update it to 15.0-REL, but...
The 14bot is running 14.3p13, but an update to 14.4pX is planned.

What are Refleaks builds ?

[opsec]

Ah, ref-leaks builds. Interesting...

[vstinner]

Refleaks checks for memory leaks, file descriptor leaks, Python reference leaks, etc.

[encukou]

or from the buildbot operator view: Refleaks are the slow builds that don't run as often.

[zware]

I'm going to take lack of dissent as assent and go ahead with this :)

@opsec if this turns out to be more load than you want on your worker, we can always just drop it.