Bug in `names<-.epi_df`

The attributes of `x` are potentially changed, but this has no impact on the return value.  `x` here should probably be `result`, or `result, result` should be `result, x`.
```{r}
[...]
  result = NextMethod()
  attributes(x)$metadata$other_keys <- value[match(old_other_keys, old_names)]
  dplyr::dplyr_reconstruct(result, result)
```
This would break the removed-other_keys-dropping.