composer.json specifies non-existant dependency

[gmcinnes]

It asks for "pixline/php_codesniffer_wp_standard": "dev-master",
but that repo doesn't appear to exist, alas 😦

[pixline]

My fault: it was supposed to be an interim repository and then deleted but somewhat slipped in the opensource repository, sorry for that.

Temporary workaround:

1. Install https://github.com/squizlabs/PHP_CodeSniffer
2. Install https://github.com/WordPress-Coding-Standards/WordPress-Coding-Standards
3. Remove the repository from composer.json