Update PhpStan

[oleibman]

Too many errors when Dependabot tried. These seem mostly to involve implode, whose use is often embedded in other function calls. For that reason, these changes include a higher proportion than usual of // @phpstan-ignore-line.

This is:

• a bugfix
• a new feature
• refactoring
• additional unit tests
• update development tools

Checklist:

• Changes are covered by unit tests
  • Changes are covered by existing unit tests
  • New unit tests have been added
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change and a link to the pull request if applicable
• Documentation is updated as necessary

[oleibman]

Coveralls is complaining because a line which was uncovered before was changed by the addition of phpstan-ignore-line, so it looks like a "new" uncovered statement, but it isn't really. This involves ribbon objects, which I am not willing to look at.