Replace internal calls to helpers with StaticInflector

[donatj]

So while you have this warning, the library itself currently leans on these helpers, so much of the does not work without requiring vendor/icanboogie/inflector/lib/helpers.php

Warning

Since v3.0 the file with the helper functions is no longer included in the
autoload.
You need to include the file vendor/icanboogie/inflector/lib/helpers.php
in your composer.json if you want to continue using these functions.

So for instance

<?php

require 'vendor/autoload.php';

use ICanBoogie\Inflector;

echo Inflector::get('en')->pluralize('soup');

currently throws

Fatal error: Uncaught Error: Call to undefined function ICanBoogie\upcase() in /Users/jdonat/Sites/myon/vendor/icanboogie/inflector/lib/Inflections.php on line 255

This PR just changes all the call sites where the helpers are being used internally to use the static inflector instead of helpers

[donatj]

I also swapped ubuntu-20.04 with ubuntu-latest in your CI tests, as ubuntu-20.04 is no longer supported by GitHub actions. I can pull this change out if you are so inclined.

[coveralls]

coverage: 94.475%. remained the same
when pulling c6e5ea6 on donatj:fix/user-statics-internally
into c6fcdf4 on ICanBoogie:main.

[olvlvl]

Thank you! That's a great catch. I should have removed require __DIR__ . '/../lib/helpers.php'; from the test bootstrap. Let's remove the bootstrap altogether now.

I've updated the Ubuntu version in another commit. Could you rebase your branch?

[olvlvl]

I opened a PR #45

[donatj]

Ok, I rebased my branch ;)

One note - I'd had used ubuntu-latest, I see you're using ubuntu-22.04 -

It's personal preference of course, but in my own repos I trust Ubuntu to continue working across stable releases more than I trust myself to remember to update all of my GitHub Actions every time GitHub deprecates a release.

Anyway, thanks for the project! I've been using it for years!

[olvlvl]

@donatj Thank you for your contribution. I published v3.0.1 with our changes.