Ensure that adlistFile is created before chmodding

If an user installs Pi-hole without selecting any adlists, the installer emits a warning and exits. By touching the file this is prevented.

automated install/basic-install.sh

@@ -1228,6 +1228,7 @@ chooseBlocklists() {
     do
         appendToListsFile "${choice}"
     done
+    touch "${adlistFile}"
     chmod 644 "${adlistFile}"
 }