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

This PR fixes the folowing CI failure.

```console
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:81:in `block in <main>'
     # tasks/spec_runner.rake:29: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:117:in `block in <main>'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/task.rb:271:in `block in execute'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/task.rb:271:in `execute'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/task.rb:213:in `block in invoke_with_call_chain'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/task.rb:193:in `invoke_with_call_chain'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/task.rb:182:in `invoke'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/application.rb:160:in `invoke_task'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/application.rb:116:in `block in top_level'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/application.rb:116:in `block in top_level'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/application.rb:125:in `run_with_threads'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/application.rb:110:in `top_level'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/application.rb:83:in `block in run'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/application.rb:186:in `standard_exception_handling'
     # /usr/local/bundle/gems/rake-12.3.1/lib/rake/application.rb:80:in `run'
     # /usr/local/bundle/gems/rake-12.3.1/exe/rake:27:in `<main>'

Finished in 1 minute 41.88 seconds (files took 12.35 seconds to load)
22837 examples, 1 failure, 7 pending

Failed examples:

rspec ./spec/project_spec.rb:80 # RuboCop Project changelog has newline at end of file
```

https://circleci.com/gh/rubocop-hq/rubocop/21552

palkan/rubocop,tejasbubane/rubocop,tdeo/rubocop,jfelchner/rubocop,panthomakos/rubocop,mikegee/rubocop,maxjacobson/rubocop,deivid-rodriguez/rubocop,tejasbubane/rubocop,bbatsov/rubocop,tejasbubane/rubocop,rrosenblum/rubocop,vergenzt/rubocop,meganemura/rubocop,smakagon/rubocop,rrosenblum/rubocop,panthomakos/rubocop,deivid-rodriguez/rubocop,maxjacobson/rubocop,meganemura/rubocop,petehamilton/rubocop,bquorning/rubocop,jmks/rubocop,vergenzt/rubocop,tdeo/rubocop,bquorning/rubocop,deivid-rodriguez/rubocop,jfelchner/rubocop,smakagon/rubocop,bquorning/rubocop,petehamilton/rubocop,mikegee/rubocop,sue445/rubocop,panthomakos/rubocop,tdeo/rubocop,jfelchner/rubocop,jmks/rubocop,mikegee/rubocop,sue445/rubocop,palkan/rubocop,sue445/rubocop,jmks/rubocop,rrosenblum/rubocop,petehamilton/rubocop,palkan/rubocop,meganemura/rubocop,maxjacobson/rubocop,bbatsov/rubocop,vergenzt/rubocop