Log Message:
devel/ruby-rspec-mocks: update to 3.8.0

### 3.8.0 / 2018-08-04
[Full Changelog](http://github.com/rspec/rspec-mocks/compare/v3.7.0...v3.8.0)

Bug Fixes:

* Issue error when encountering invalid "counted" negative message \ 
expectations.
  (Sergiy Yarinovskiy, #1212)
* Ensure `allow_any_instance_of` and `expect_any_instance_of` can be temporarily
  supressed. (Jon Rowe, #1228)
* Ensure `expect_any_instance_of(double).to_not have_received(:some_method)`
  fails gracefully (as its not supported) rather than issuing a `NoMethodError`.
  (Maxim Krizhanovsky, #1231)