update .travis.yml

Author: annikoff

.travis.yml

@@ -28,6 +28,7 @@ before_install:
   - if [[ $(ruby --version | awk '{print $2}') < 2.1 ]]; then
     echo "gem 'nokogiri', '= 1.5.11'" >> $REDMINE_PATH/Gemfile; fi
   - sed -ri 's/("selenium-webdriver")/\1, "= 2.53.4"/' $REDMINE_PATH/Gemfile
+  - sed -ri 's/("minitest")/\1, "= 5.10.1"/' $REDMINE_PATH/Gemfile
   - cd $REDMINE_PATH
   - if [[ $REDMINE_VER < '3.2-stable' ]]; then
     echo "$(curl http://www.redmine.org/projects/redmine/repository/revisions/14891/diff/trunk/lib/tasks/redmine.rake?format=diff)" > redmine.rake.patch;