To update mintty packaged with msys2, first download the latest version of mintty from here. Download
the mintty tarball and extract it. Then copy mintty.exe
to MSYS2_ROOT/usr/bin
to replace the old mintty.exe
file.
Restart msys2 and you should be albe to use the latest mintty. Reference here.
Install the latest wsltty release from here. Mintty will be updated.