Remove unnecsseary lines

[mrrobot47]

Need to remove:

https://github.com/rtCamp/rtcamp-wordpress-mu/blob/23e36e5347bc16b0659e487e27067b19b2048638/.github/hosts.yml#L16-L20

Need to ensure that the KNOWN_HOSTS file is inside $GITHUB_WORKSPACE.

  # Setting these options because of ssh-issues in GH actions.
  # Should not be needed in future, hopefully :fingers-crossed:
  sshOptions:
    UserKnownHostsFile: /dev/null
StrictHostKeyChecking: no