Module name in decorator isn't renamed

Input file:

```python
import attr


@attr.s()
class A:
  ...
```

Code:

```python
import bowler
bowler.Query('tmp.py').select_module('attr').rename('testme').execute(write=True, silent=True)
```

Output file:

```python
import testme


@attr.s()
class A:
  ...
```

Attr was renamed in the import statement, but not in the decorator.