PHPStan CI

[spaze]

• Fix errors reported by PHPStan (nulls instead of strings & ints in a test file)
• Run PHPStan in CI
• ... and on PRs

I'd also recommend protecting the default branch in repo settings and making the tests required before a PR can be merged.

[antonioribeiro]

Hey @spaze, thanks for this PR. We just need you to, please, sign your commits so we can approve it:

https://docs.github.com/articles/about-gpg/ https://dev.to/zahrakhadijha/git-fixing-unsigned-gpg-commits-phn

[spaze]

Hey, sorry missed the check. All commits now signed, thanks!