Dispatch issue with `set_style` for `LocTitle`

[jrycw]

It seems that the dispatch of set_style for LocTitle is still under development and hasn't been made public yet. However, the implementation seems a bit off because return data._styles.append(info) will return None, which behaves differently compared to other functions in the same module.

https://github.com/posit-dev/great-tables/blob/14ce2c53753203b9d01034d89b5ed12706726711/great_tables/_locations.py#L402