[3.12] GH-106330: Fix matching of empty path in `pathlib.PurePath.match()` (GH-106331) (GH-106372)

We match paths using the `_lines` attribute, which is derived from the
path's string representation. The bug arises because an empty path's string
representation is `'.'` (not `''`), which is matched by the `'*'` wildcard.
(cherry picked from commit b4efdf8cda8fbbd0ca53b457d5f6e46a59348caf)