`unnecessary-pass` (`PIE790`) only checks for docstrings immediately followed by a `pass` statement

Currently, `PIE790` triggers on

```python
def foo():
    """A docstring."""
    pass
```

as expected. However, it does not trigger on

```python
def foo():
    print("foo")
    pass
```

or

```python
def foo():
    """A docstring."""
    print("foo")
    pass
```

which is unexpected.
