gh-152762: Fix zipfile.Path.is_symlink() raising KeyError for missing entries

[UditDewan]

zipfile.Path.is_symlink() called ZipFile.getinfo() unguarded, so it raised KeyError for any path not present in the archive:

import io, zipfile

buf = io.BytesIO()
with zipfile.ZipFile(buf, "w") as zf:
    zf.writestr("present.txt", b"x")

buf.seek(0)
with zipfile.ZipFile(buf) as zf:
    p = zipfile.Path(zf) / "missing.txt"
    p.exists()      # False
    p.is_file()     # False
    p.is_dir()      # False
    p.is_symlink()  # KeyError: "There is no item named 'missing.txt' in the archive"

The same KeyError was raised for the archive root (zipfile.Path(zf)) and for implied directories, since neither has a ZipInfo entry backing it.

This change catches the KeyError from getinfo() and returns False, so is_symlink() behaves like the neighboring predicates (exists(), is_file(), is_dir()) and like pathlib.Path.is_symlink() on a missing filesystem path. Existing symlink entries are unaffected.

Added a test covering the missing-entry, root, and implied-directory cases (all raise KeyError without the fix), and a NEWS entry.

• Issue: zipfile.Path.is_symlink() raises KeyError for missing entries #152762

[python-cla-bot]

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