Add Named Args to Tests; Bump to PHP 8.0+

[n7studios]

Summary

Adds named arguments to tests for readability, which should help with reviewing future PRs that introduce the v4 API and changed parameter options.

Bumps minimum supported PHP version to 8.0 to support named arguments (8.1 and higher are officially supported by PHP, so likely we'll bump to 8.1 with the v4 API support: https://www.php.net/supported-versions.php). Users of 7.4 and lower can continue to use 1.3 of our SDK.

Testing

Existing tests pass.

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• The code passes when running PHPStan
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)

[noelherrick]

Makes sense. What's your general guideline for when you deprecate a PHP version? I checked 7.4 was EOL'd in 2022.

[n7studios]

Makes sense. What's your general guideline for when you deprecate a PHP version? I checked 7.4 was EOL'd in 2022.

Typically deprecate ~ 1 year after its security fixes only have ended. There are some package statistics, but they get skewed when our unit tests run, so can't be accurately relied on.