Fix complaint about Apple-specific ssh arguments

[unixorn]

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Describe the bug

On 12.4, we see a deprecation warning about ssh's Apple-specific flags.

WARNING: The -K and -A flags are deprecated and have been replaced
         by the --apple-use-keychain and --apple-load-keychain
         flags, respectively.  To suppress this warning, set the
         environment variable APPLE_SSH_ADD_BEHAVIOR as described in
         the ssh-add(1) manual page.

Expected behavior No complaints about deprecation

Desktop (please complete the following information):

• OS/distro: macOS
• Version 12.4

[jfmcdowell]

Did PR #136 not fix this after all?

[unixorn]

Maybe the warning was added before Monterey and I only noticed it then?

[unixorn]

Closed by #228