Use `composer install` instead of `composer update`
Created by: edg2s
The former respects composer.lock
files if they exist, as is
recommended by https://getcomposer.org/doc/01-basic-usage.md#commit-your-composer-lock-file-to-version-control,
and is the command given in installation instructions, e.g.
https://www.mediawiki.org/wiki/Extension:TemplateStyles
Add the composer.lock for Patch demo itself.