Update supported FreeBSD to 13.1

[SeanTAllen]

[ponylang-main]

Hi @SeanTAllen,

The changelog - changed label was added to this pull request; all PRs with a changelog label need to have release notes included as part of the PR. If you haven't added release notes already, please do.

Release notes are added by creating a uniquely named file in the .release-notes directory. We suggest you call the file 4185.md to match the number of this pull request.

The basic format of the release notes (using markdown) should be:

## Title

End user description of changes, why it's important,
problems it solves etc.

If a breaking change, make sure to include 1 or more
examples what code would look like prior to this change
and how to update it to work after this change.

Thanks.

[SeanTAllen]

Need to update to not build googlebench on Windows right now as it doesn't work. Then this is good for review.

[SeanTAllen]

@kulibali I've updated this to try benchmark 1.7.1

[chalcolith]

Thanks @SeanTAllen, 1.7.1 seems to work for me on Windows.

[SeanTAllen]

I'll squash and merge this tomorrow.