Update workflows

[codemasher]

Hey,

this PR updates the workflow runs to use the latest versions of actions/checkout and ramsey/composer-install to stop the node.js deprecation warnings.

Further I have moved the PHPUnit cache directory under .build/.phpunit.cache (now looking at it, the leading . is a bit unnecessary) and cleaned up the .gitignore.

Cheers!

[lcobucci]

Thanks for the patch.

What's the benefit in changing the phpunit cache location to you?

[codemasher]

This is a standard practice in all my projects

• no random unrelated directories in the project root, the other (temporary) PHPUnit output paths (coverage, logs) are already in .build
• easy to .gitignore anything not project related
• only have to exclude only a single directory in the IDE (other than vendor)

Actually, we could do the same with the .phpbench directory, but i haven't looked at where it is created, nor ran it locally yet.

[lcobucci]

@codemasher I've rebased this branch on top of the latest changes, keeping only the changes that make sense to me.

Thank you for contributing!