Revert "Update .travis.yml to test with 5.26.0"
Revert "Update .travis.yml to test with 5.26.0"

This reverts commit 1c04acbe21e60be8a99b92c8ba7940b421f8ad6d.

Sadly there is a lot of breakage because some modules (which use
Module::Install) just won't install at all under 5.26.0.

autarch/DateTime.pm,autarch/DateTime.pm