chore: add PHP 8.4 to CI

[phil-davis]

Let's see if GitHub knows about PHP 8.4 alpha yet.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.18%. Comparing base (9d02602) to head (fd602f9).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #124   +/-   ##
=========================================
  Coverage     99.18%   99.18%           
  Complexity      111      111           
=========================================
  Files             7        7           
  Lines           370      370           
=========================================
  Hits            367      367           
  Misses            3        3           

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[staabm]

I would be fine with skipping cs-fixer for 8.4 for now

[staabm]

(or maybe we just need to update cs-fixer)

[phil-davis]

I would be fine with skipping cs-fixer for 8.4 for now

I just want to see if it reports anything interesting (it shouldn't!), and it passed like this.

Now to look at the phpstan deprecation messages.

[phil-davis]

The deprecation messages are all for vendor packages. And some are inside vendor, phpstan, vendor again - dependencies of phpstan itself.

So various dependencies need to be "fixed" first anyway.

[phil-davis]

See PR #126 for the 5.1 branch. We can get that approved and merged first, then I will see what finally should be done here in master.

[phil-davis]

See #136