Fix NixOS uptime.

ufetch-nixos

@@ -9,7 +9,7 @@
 host="$(hostname)"
 os="$(nixos-version)"
 kernel="$(uname -sr)"
-uptime="$(uptime -p | sed 's/up //')"
+uptime="$(uptime | awk -F, '{sub(".*up ",x,$1);print $1}' | sed -e 's/^[ \t]*//')"
 packages="$(ls -d -1 /nix/store/ | wc -l)"
 shell="$(basename ${SHELL})"
 if [ -z "${WM}" ]; then