Delete REQUIRE

[DilumAluthge]

We no longer have any test-only dependencies, so we can delete test/REQUIRE.

[codecov-io]

Codecov Report

Merging #239 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #239   +/-   ##
=======================================
  Coverage   90.11%   90.11%           
=======================================
  Files           6        6           
  Lines         344      344           
=======================================
  Hits          310      310           
  Misses         34       34

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[DilumAluthge]

The Travis "failures" on Travis CI - Branch and Travis CI - Pull Request are due to some problem in the interaction between staging.travis-ci.com and Coveralls. It seems that Coveralls does not accept coverage reports when they are submitted from staging.travis-ci.com.

The correct Travis builds are continuous-integration/travis-ci/pr and continuous-integration/travis-ci/push (these correspond to travis-ci.org builds). Those Travis builds are passing.