Merge branch 'ps/apply-beyond-symlink' into maint-2.30

Fix a vulnerability (CVE-2023-23946) that allows crafted input to trick
`git apply` into writing files outside of the working tree.

* ps/apply-beyond-symlink:
  dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
