Pro Sites - need to update Registration.php to before the (Must be..

When registering a site, the username input field has "(Must be at least 4 characters, letters and numbers only.)" where it is wrapped on the same line. See attachment.

I found in the Registration.php located at /htdocs/wp-content/plugins/pro-sites/pro-sites-files/lib/ProSites/View/Front/

We just need to add "" to the end of this ...... '" maxlength="60" />'; on line 138 like line 147.

I know I can just make the change, but will lose it on the next update. Can I do anything on the a child theme side to overwrite this? Or just make the change to the file and watch for the next update.