mruby-set no longer depends on mruby-metaprog by introducing the internal `_hash` method.
The `instance_variable_get` has been separated to `mruby-metaprog` gem, so we need to specify the gem as test dependency.
git-subtree-dir: mrbgems/mruby-set git-subtree-mainline: 3b55a09f91 git-subtree-split: 68334311ac
3b55a09f91
68334311ac