Workaround for cc-test-reporter with SimpleCov 0.18

[koic]

This PR fixes the following build error when using cc-test-reporter with SimpleCov 0.18.

% #!/bin/bash -eo pipefail
  ./cc-test-reporter before-build
  rake coverage
  ./cc-test-reporter after-build --exit-code $?

(snip)

Coverage report generated for RSpec to
/home/circleci/project/coverage. 5051 / 5064 LOC (99.74%) covered.
Error: json: cannot unmarshal object into Go struct field input.coverage
of type []formatters.NullInt

https://circleci.com/gh/rubocop-hq/rubocop-rspec/10604

This patch is a workaround until the following issue will be resolved.
qltysh-archive/test-reporter#418

---

Before submitting the PR make sure the following are checked:

• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the changelog if the new code introduces user-observable changes.
• The build (bundle exec rake) passes (be sure to run this locally, since it may produce updated documentation that you will need to commit).

If you have created a new cop:

• Added the new cop to config/default.yml.
• The cop documents examples of good and bad code.
• The tests assert both that bad code is reported and that good code is not reported.

[bquorning]

Thanks!

I wonder is anyone is using rubocop-rspec’s Code Climate page at all.