Homebrew apparently requires you to now specify the version of the package
you're updating. We previously could just run `brew update openssl` and it
would work. Now we must run `brew update openssl@1.1` for the command to
succeed.
Using `brew update-reset` causes homebrew to reset to homebrew's HEAD commit, which may
be buggy and broken. It appears whatever Cirrus was doing previously on their Catalina
VM is no longer a problem, and so update-reset isn't required anymore. Switch to
`brew update` to make sure we still get newer versions of the packages, but is
actually a versioned release of homebrew.
This fixes some issues with the Catalina builds when it prepares the image
and the base Cirrus image has old recipes for Homebrew. The VM then has
to build a bunch of packages it shouldn't need to.
- Upgrade the Big Sur VM to use the Xcode 12.5 version. This has a newer
version of brew installed on it that fixes an issue with an EOL package host
that finally shut down for good recently.
- Use 'brew upgrade' for openssl and cmake, since those are both present on the
base VM. This prevents 'brew install' from printing an error if the package
exists but is out of date.
