.travis.yml in itamae-1.10.2 vs .travis.yml in itamae-1.10.3

@@ -1,39 +1,36 @@
 language: ruby
 sudo: required
+dist: xenial
 services:
   - docker
 rvm:
   - 2.3
   - 2.4
   - 2.5
+  - 2.6
   - ruby-head
 bundler_args: "--jobs=4 --retry=3"
 cache:
   bundler: true
-  directories:
-    - $HOME/docker
 
-before_cache:
-  # Save tagged docker images
-  - >
-    mkdir -p $HOME/docker && docker images -a --filter='dangling=false' --format '{{.Repository}}:{{.Tag}} {{.ID}}'
-    | xargs -n 2 -t sh -c 'test -e $HOME/docker/$1.tar.gz || docker save $0 | gzip -2 > $HOME/docker/$1.tar.gz'
-
 before_install:
-  - gem update --system --no-document
-  - gem install bundler --no-document
-  # Load cached docker images
-  - if [[ -d $HOME/docker ]]; then ls $HOME/docker/*.tar.gz | xargs -I {file} sh -c "zcat {file} | docker load"; fi
+  - travis_retry gem update --system || travis_retry gem update --system 2.7.8
+  - travis_retry gem install bundler --no-document || travis_retry gem install bundler --no-document -v 1.17.3
 
 script:
   - bundle exec rake spec
 notifications:
   email: false
   slack:
     secure: PcecHsVS6lw89K5PllW8xFlzu0d04p6lYfxlUZL0/yp9flAczElJME4RshSMSkbnu5e2Iw8KUA2xB1jkAzDo9qYoXveaKyjkFUOb1ZxYIVxzzfoDDwUNTMmSoyjZjvbeBUcpxxmxy6nXa3zS+gA2ohqWhS9WTTlTqyM5RriDjZ8=
 matrix:
   allow_failures:
   - rvm: ruby-head
+  include:
+  - rvm: 2.6
+    env: RUBYOPT="--jit"
+  - rvm: ruby-head
+    env: RUBYOPT="--jit"
 branches:
   only:
   - master