Updating PHP dependencies: Slim, dotenv, phpunit

[Mark-H]

As can be witnessed in the closed pull requests from Dependabot linked below, we're a little behind on a bunch of PHP dependencies. This includes major updates with breaking changes that require code changes.

Help with this would be appreciated.

• Slim 3 to 4 https://www.slimframework.com/docs/v4/start/upgrade.html
• dotenv 3 to 5 https://github.com/vlucas/phpdotenv/blob/v5.0.0/UPGRADING.md#v3-to-v4, https://github.com/vlucas/phpdotenv/blob/v5.0.0/UPGRADING.md#v4-to-v5
• phpunit 7 to 9 - low prio because there's not much of a test suite to talk off

[Mark-H]

There's a €50 bounty on getting these packages upgrade.

[diegog956]

I can take a pass at this.

Plan:

1. Upgrade Slim, phpdotenv, and PHPUnit dependencies.
2. Apply the Slim 4 bootstrap/middleware/request-response changes needed by the app.
3. Run the Docker-based install and test suite before opening the PR.

[radiantjade]

Submitted PR #376 with the Slim 4, phpdotenv 5, and PHPUnit 9 upgrade: #376

Verification run locally:

• composer validate --strict
• php docs.php sources:init
• composer test
• find src tests public -name '*.php' -print0 | xargs -0 -n1 php -l

[diegog956]

I see #376 was submitted for this upgrade while I was validating locally, so I will step back to avoid duplicating the same work.

[KHHH2312]

I'll take a look at this and start working on updating the dependencies!

[Mark-H]

Apologies for not being more responsive, but this work was already done a while ago in #355 which has been running on the docs mirror. I do need to check into if it was deployed to production yet, that needed some version upgrades.