Update travis config.

Author: gkellogg

.travis.yml

@@ -1,23 +1,17 @@
 language: ruby
 bundler_args: --without debug
 script: "bundle exec rspec spec"
-before_install:
-  - 'gem update --system --conservative || (gem i "rubygems-update:~>2.7" --no-document && update_rubygems)'
-  - 'gem update bundler --conservative'
 env:
   - CI=true
 rvm:
-  - 2.2
-  - 2.3
   - 2.4
   - 2.5
   - 2.6
-  - jruby-9
-  - rbx-3
+  - 2.7
+  - jruby
 cache: bundler
 sudo: false
 matrix:
   allow_failures:
-    - rvm: jruby-9
-    - rvm: rbx-3
+    - rvm: jruby
 dist: trusty