Better summary detection (no dot added in the middle of a sentence)

[Pierre-Sassoulas]

In the following example pydocstringformatter add a .\n after "that".

def _looks_like_subscriptable(node: ClassDef) -> bool:
    """
    Returns True if the node corresponds to a ClassDef of the Collections.abc module that
    supports subscripting
    """
    pass

It would be nice to detect summary better, see pylint-dev/astroid#1792 (comment)