Insert a newline at EOF of CHANGELOG.md
Insert a newline at EOF of CHANGELOG.md

This commit fixes the folowing CI failure.

```console
% bundle exec rake

(snip)

==> Failures

  1) RuboCop Project changelog has newline at end of file
     Failure/Error: expect(changelog.end_with?("\n")).to be true

       expected true
            got false
     # ./spec/project_spec.rb:91:in `block (3 levels) in
            <top (required)>'
     # tasks/spec_runner.rake:67:in `run_worker'
     # tasks/spec_runner.rake:27:in `block in run_specs'
     # tasks/spec_runner.rake:41:in `with_encoding'
     # tasks/spec_runner.rake:25:in `run_specs'
     # tasks/spec_runner.rake:112:in `block in <top (required)>'
```

https://circleci.com/gh/rubocop-hq/rubocop/48849

rrosenblum/rubocop,maxjacobson/rubocop,maxjacobson/rubocop,tdeo/rubocop,maxjacobson/rubocop,vergenzt/rubocop,jmks/rubocop,mikegee/rubocop,meganemura/rubocop,panthomakos/rubocop,vergenzt/rubocop,smakagon/rubocop,deivid-rodriguez/rubocop,jmks/rubocop,vergenzt/rubocop,meganemura/rubocop,rrosenblum/rubocop,bbatsov/rubocop,mikegee/rubocop,tejasbubane/rubocop,tejasbubane/rubocop,tdeo/rubocop,bbatsov/rubocop,jfelchner/rubocop,rrosenblum/rubocop,jfelchner/rubocop,jfelchner/rubocop,deivid-rodriguez/rubocop,tdeo/rubocop,mikegee/rubocop,tejasbubane/rubocop,smakagon/rubocop,panthomakos/rubocop,panthomakos/rubocop,meganemura/rubocop,jmks/rubocop,deivid-rodriguez/rubocop