Travis CI: Fix for "Remove executables" prompt
Travis CI: Fix for "Remove executables" prompt

Rubygems is prompting "Remove executables: bundler in addition to the
gem? [Yn]" during the `rvm install 2.6.5` command. Pipe `yes` into that
command to keep the build going.

konklone/oversight.io,konklone/oversight.io,konklone/oversight.io,konklone/oversight.io