Log Message:
Update ruby-minitest to 5.10.3.

=== 5.10.3 / 2017-07-21

* 1 minor enhancement:

  * Extended documentation for Mock#expect for multiple calls to mock object.
    (insti)

* 2 bug fixes:

  * Finished off missing doco.
  * Fixed verbose output on parallelize_me! classes. (chanks)