Rails 6.0 requires Ruby 2.4.1 or higher
Rails 6.0 requires Ruby 2.4.1 or higher

```console
43.16s$ bundle install --jobs=3 --retry=3
Your Gemfile lists the gem sqlite3 (>= 0) more than once.
You should probably keep only one of them.
While it's not a problem now, it could cause errors if you change the
version of one of them later.
Fetching https://github.com/rails/arel.git
Fetching https://github.com/rails/rails.git
Fetching gem metadata from https://rubygems.org/...........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies......
activesupport-6.0.0.alpha requires ruby version >= 2.4.1, which is
incompatible
with the current version, ruby 2.2.10p489
```

https://travis-ci.org/koic/gtm_rails/jobs/366371380#L739-L749

koic/gtm_rails