Allow the parsing of composer 2 installed.json

[philipheimboeck]

This PR allows to parse the installed.json generated by composer 2 as the format changed.
Due to this change it was not possible anymore to get the current versions of the installed tools.

https://getcomposer.org/upgrade/UPGRADE-2.0.md

vendor/composer/installed.json format changed:

• packages are now wrapped into a "packages" top level key instead of the whole file being the package array

[ndench]

Thanks @philipheimboeck! I'm running into this issue as well.

Do you have any idea why CI would be failing?

  [RuntimeException] 
  Could not scan for classes inside "C:\projects\phpqa\vendor/sebastian/phpcpd/src/" which does not appear to 
  be a file nor a folder   

Looks like some issue with running on windows tbh. I doubt this PR caused it though.
The error isn't present on other PRs, but they are all much older. Maybe it's an issue with composer 2.0?

[ndench]

I've been using this fork for a couple of weeks now and it works fine. Any chance we can get this merged soon?

[ptondereau]

any news on it?

[zdenekdrahos]

It's going to be fixed in 0e0ce89.