Log Message:
security/ruby-net-ssh: update to 6.1.0

Update to ruby-net-ssh 6.1.0.

=== 6.1.0

  * adapt to ssh's default bahaviors when no username is provided.
    When Net::SSH.start user is nil and config has no entry
    we default to Etc.getpwuid.name() instead of Etc.getlogin(). [#749]

=== 6.1.0.rc1

  * Make sha2-{256,512}-etm@openssh.com MAC default again [#761]
  * Support algorithm subtraction syntax from ssh_config [#751]