Migrate from ember-data@~3.8.0 to ember-data@^3.8.0 #209
Description
In #208 we were forced to use ~3.8.0 because ember-data@3.9.0 has a fundamental issue in fastboot (and was causing our own tests to fail).
As of warp-drive-data/warp-drive#6011, this should no longer be the case and once ember-data@3.9.1 is published we should be able to update this library to use ^3.8.0 again.