Make a temporary directory in $XDG_RUNTIME_DIR instead of $PASSWORD_STORE_DIR.
$XDG_RUNTIME_DIR defaults to /run/user/$uid/. This directory has the security advantage of only being readable and writable by the current user and being mounted in RAM, causing the screenshot to be fully wiped on shutdown and not needing shred, which doesn't work reliably on SSD's.
Also quoted $dir, for the off chance someone has spaces in their $PASSWORD_STORE_DIR.
Removed the check for xclip and the $issuer and $name variables, as they are unused.
If you're wondering why echo is piped into dmenu, on my system dmenu hung when called without the pipe, causing the whole script to freeze.
