[BUGFIX] Support composer.lock in sub directory of git repository

[thommyhh]

Determine path of composer.lock relative to git root directory to
correctly get HEAD version of composer.lock.

[thommyhh]

@markus-k Don't know, if you're still using or maintaining this.

In my current setups the composer.lock is located in a sub directory of the git repository. The current version assumes, that it is directly in the git repository root, leading to an error.

[markus-k]

I haven't touched PHP in years, so no. Maybe @thomashempel is still using it?

[thommyhh]

@markus-k Can you update it anyway or transfer the NPM package to me. If Thomas doesn't use/want to maintain it.

[markus-k]

I don't have write access to this repository anymore, so I can't do much.

[thommyhh]

@markus-k I don't want the repo, I already made a fork. I want the NPM package on NPMJS.org. It says, you're the only contributer.

[markus-k]

Oh! Well I would, but my account seems broken. Password reset results in Service Unavailable...

[markus-k]

BTW, it's still broken.

[thommyhh]

@markus-k What do you mean by "broken"? If you can't enter a generated password, try removing symbols from the password. I've had diffculties with symbols in password on several sites.

[markus-k]

I was finally able to reset my password, I added you as a maintainer.