[kitchen/travis] Not working on new pre-salted `ubuntu-20.04` image

[myii]

Identified during weekly master branch testing. Quite a few formulas are already working with ubuntu-20.04.

• https://travis-ci.org/github/myii/iscsi-formula/builds/692447613

Still working with ubuntu-18.04, though:

• https://travis-ci.org/github/myii/iscsi-formula/builds/692874714

[noelmcloughlin]

I'll look at this after https://github.com/saltstack-formulas/iscsi-formula/pull/36 is merged.

[myii]

@noelmcloughlin Sure, I'll try to get around to that soon.

[myii]

I'll look at this after #36 is merged.

36 has been merged now and 20.04 is already available in Kitchen and Travis (commented out). Also note the comment here:

• https://github.com/saltstack-formulas/iscsi-formula/pull/36#issuecomment-637810244