neovim: Exclude temp files from persistent undo

Otherwise it is possible to restore cleartext passwords from pass or
sops from the undo files.

users/simon/modules/neovim/init.lua

@@ -41,6 +41,8 @@ cmd('colorscheme solarized')
 opt.undofile = true
 opt.undolevels = 4096
 opt.undoreload = 16384
+cmd('autocmd BufWritePre /dev/shm/* setlocal noundofile') -- exclude pass
+cmd('autocmd BufWritePre /tmp/* setlocal noundofile') -- exclude sops
 
 -- Behaviour
 opt.hidden = true -- background buffers