tails-debugging-info: quote one last variable in debug_file().

Currently we don't pass this function anything that requires quoting,
but let's be a bit more defensive.

Will-fix: #8991

config/chroot_local-includes/usr/local/sbin/tails-debugging-info

@@ -9,7 +9,7 @@ debug_command() {
 debug_file() {
     echo
     echo "===== content of $1 ====="
-    cat $1
+    cat "$1"
 }
 
 debug_command /usr/sbin/dmidecode -s system-manufacturer