Update simplecov and coveralls gem versions
Update simplecov and coveralls gem versions

The simplecov gem at version 0.12.0 gives the Ruby 2.4 Fixnum
deprecation warning. Version 0.13.0 fixes the warning, but is
incompatible with coveralls before version 0.8.23, and in that
version, simplecov is locked to 0.16.1.

gchan/password_blacklist,gchan/password_blacklist