`helpful-string` incorrectly triggers on every generic

### Describe the problem, ie expected/actual result (if it's not blatantly obvious)

_No response_

### Gist to reproduce

```python
from typing import TypeVar

_T = TypeVar("_T", bound=int)


def asdf(a: _T, b: int):
    print(f"{a}") # error: The type "_T@asdf" doesn't define a __format__, __str__ or __repr__ [helpful-string]
    print(f"{b}")
```