Remove line-length limit from editorconfig (#1525)

We don't enforce this via formatting anyway, so it doesn't help to have
it specified here.

As an alternative, we could add the following to `fourmolu.yaml` (
thanks for the hint @ffakenz ):

```
column-limit: 80
```

which would make fourmolu do a best-effort to agree with the limit, but
even then that doesn't work perfectly:


![image](https://github.com/user-attachments/assets/af1974d2-d25f-48f9-8986-6fc17d54b906)

i.e. the red line shows that it still breaks occasionally.

.editorconfig

@@ -10,7 +10,6 @@ insert_final_newline = true
 
 [*.hs]
 indent_size = 2
-max_line_length = 80
 
 [*.py]
 indent_size = 4