Setup Fallback Mirrors for pkg.freebsd.org #1162
Description
In at least 3 separate workflow runs, we've had failures due to an inability to resolve pkg.freebsd.org. Normally, mirrors should be made available based on GeoDNS and automatically handled, however, it might be worth looking up a few and using logic similar in #1132 (specifically, commit aac375a) to handle when the default gateway fails, or use other mirrors if possible. Less than ideal, but this might be necessary.
https://github.com/cross-rs/cross/actions/runs/3565770837/jobs/5991488382#step:10:28393
https://github.com/cross-rs/cross/actions/runs/3567054500/jobs/5994404235#step:10:28387
https://github.com/cross-rs/cross/actions/runs/3566358814/jobs/5992830213#step:10:28390