before_install:
  - gem update --system
  - gem update bundler
rvm:
  - 2.3.8
  - 2.4.6
  - 2.5.5
  - 2.6.3
  - 2.6.3
  - 2.7.0-preview1
  - rbx-2
  - ruby-head
  - jruby-9.1.17.0
  - jruby-9.2.7.0
  - jruby-head
jdk: openjdk8
matrix:
  allow_failures:
    - rvm: jruby-head
    - rvm: ruby-head
    - rvm: rbx-2

before_install:
  - gem update --system
  - gem update bundler
rvm:
  - 2.3.8
  - 2.4.6
  - 2.5.5
  - 2.6.3
  - 2.7.0-preview1
  - rbx-2
  - ruby-head
  - jruby-9.1.17.0
  - jruby-9.2.7.0
  - jruby-head
jdk: openjdk8
matrix:
  allow_failures:
    - rvm: jruby-head
    - rvm: ruby-head
    - rvm: rbx-2

Remove a redundant CI matrix
Remove a redundant CI matrix

Follow up of https://github.com/bblimke/webmock/commit/0fb300aa0c753e6827821bd49aeeebd804057130.

This PR removes a redundant CI matrix.
Two Ruby 2.6.3 matrices are running.
https://travis-ci.org/bblimke/webmock/builds/591205858

I think WebMock developers can get CI results faster by
removing a redundant matrix.
