runtime(zip): escape '[' on Unix as well

runtime(zip): escape '[' on Unix as well

Problem:  After 6f1cbfc9ab483a09877e153ad130164875c40b1d fnameescape()
          is no longer called on the name of the file to be extracted.
          However, while spaces indeed don't need to be escaped, unzip
          treats '[' as a wildcard character, so it need to be escaped.
Solution: Escape '[' on both MS-Windows and Unix.

From the docs it seems '*' and '?' also need escaping, but they seem to
actually work without escaping.

fixes: neovim/neovim#29977
closes: #15427

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>