Update chezmoi.zsh to have an auto update feature

chezmoi/dot_zshrc.d/executable_chezmoi.zsh

@@ -1,3 +1,4 @@
+# completion
 (
 	set -euo pipefail
 
@@ -16,3 +17,33 @@
 	chezmoi completion zsh > "$COMPLETION_FILE"
 	chmod +x "$COMPLETION_FILE"
 )
+
+# auto update
+(
+	set -euo pipefail
+
+	# has the chezmoi repo been pulled in the last 24 hours?
+	if [ "$(date +%s -r "$(chezmoi git rev-parse -- --show-toplevel)/.git/FETCH_HEAD")" -gt $((EPOCHSECONDS-86400)) ]; then
+		exit 0
+	fi
+
+	chezmoi git pull -- --rebase
+	chezmoi diff
+
+	while true; do
+		read -r 'APPLY?apply? [y/N] '
+
+		case "${APPLY:-}" in
+			'y'|'Y'|'YES'|'yes'|'Yes')
+				echo 'applying changes'
+				chezmoi apply
+				exit 0
+				;;
+
+			'n'|'N'|'NO'|'no'|'No'|'')
+				echo 'not applying changes'
+				exit 0
+				;;
+		esac
+	done
+)