Remove unnecessary `test` task in Rakefile
Remove unnecessary `test` task in Rakefile

This task isn't running any tests and can be removed:

```
Run options: --seed 29011

Finished in 0.000925s, 0.0000 runs/s, 0.0000 assertions/s.
0 runs, 0 assertions, 0 failures, 0 errors, 0 skips
```

alphagov/collections,alphagov/collections,alphagov/collections,alphagov/collections