Protect system processes calls

[albinus]

With the upcoming Emacs 29, system process functions like list-system-processes and process-attributes work on the remote host when default-directory is remote. In order to avoid this, wrap the respective code by

(let ((default-directory temporary-file-directory))
  ...)

[medranocalvo]

@albinus, thank you for the heads up. I'll review our uses as soon as possible. By the way: thank you for excellent TRAMP!

[medranocalvo]

https://github.com/ch11ng/exwm/blob/10bd12234e896d35a2c4eafabc62a31126d23bf3/exwm.el#L131