Insert trailing comma when function breaks with single argument (#8921)
## Summary
Given:
```python
def _example_function_xxxxxxx(
variable: Optional[List[str]]
) -> List[example.ExampleConfig]:
pass
```
We should be inserting a trailing comma after the argument (as long as
it's a single-argument function). This was an inconsistency with Black,
but also led to some internal inconsistencies, whereby we added the
comma if the argument contained a trailing end-of-line comment, but not
otherwise.
Closes https://github.com/astral-sh/ruff/issues/8912.
## Test Plan
`cargo test`
Before:
| project | similarity index | total files | changed files |
|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75804 | 1799 | 1648 |
| django | 0.99984 | 2772 | 34 |
| home-assistant | 0.99963 | 10596 | 146 |
| poetry | 0.99925 | 317 | 12 |
| transformers | 0.99967 | 2657 | 322 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99980 | 3669 | 18 |
| warehouse | 0.99977 | 654 | 13 |
| zulip | 0.99970 | 1459 | 21 |
After:
| project | similarity index | total files | changed files |
|----------------|------------------:|------------------:|------------------:|
| cpython | 0.75804 | 1799 | 1648 |
| django | 0.99984 | 2772 | 34 |
| home-assistant | 0.99955 | 10596 | 213 |
| poetry | 0.99917 | 317 | 13 |
| transformers | 0.99967 | 2657 | 324 |
| twine | 1.00000 | 33 | 0 |
| typeshed | 0.99980 | 3669 | 18 |
| warehouse | 0.99976 | 654 | 14 |
| zulip | 0.99957 | 1459 | 36 |
ruff
eaa31042 - Insert trailing comma when function breaks with single argument (#8921)
