Restrict net-ssh to < 3.0 for Ruby < 2.0
Restrict net-ssh to < 3.0 for Ruby < 2.0

net-ssh 3.0 dropped support for Ruby < 2.0 causing an issue for
test-kitchen/busser:
https://github.com/test-kitchen/busser/issues/32

In summary, older versions of Chef use Ruby < 2.0. When running kitchen
tests with busser-serverspec, it tries to install the serverspec gem,
attempts to install the latest allowable net-ssh (3.0.x) and fails as it does
not support Ruby < 2.0.

minimum2scp/specinfra,sergueik/specinfra,uroesch/specinfra,tacahilo/specinfra,verisign/specinfra,stefanhorning/specinfra,hfm/specinfra,ihassin/specinfra,serverspec/specinfra,mizzy/specinfra