Security update, fixes CVE-2022-37434 in zlib.
Only applications exposing/using `inflateGetHeader()` seem to be affected,
which is not our case, so this is not critical for Godot.
Remove duplicated copy of zlib in freetype sources to force using the updated
version in `thirdparty/zlib/`.
Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>
93409b8e64