CI: added PHP 8.4 (#723) #690

Job	Run time
PHPUnit Composer v2 (PHP 7.4)	31s
PHPUnit (PHP 7.2)	2m 56s
Tests alternative autoloader (PHP 7.1)	13s
PHPUnit (PHP 7.3)	2m 49s
PHPUnit coverage (PHP 7.4)	1m 4s
Tests alternative autoloader (PHP 7.2)	6s
PHPUnit (PHP 7.4)	36s
Tests alternative autoloader (PHP 7.3)	7s
PHPUnit (PHP 8.0)	2m 53s
Tests alternative autoloader (PHP 7.4)	11s
PHPUnit (PHP 7.1)	2m 52s
PHPUnit (PHP 8.1)	2m 42s
PHPUnit lowest deps (PHP 7.3)	2m 42s
Tests alternative autoloader (PHP 8.0)	10s
PHPUnit (PHP 8.2)	2m 43s
Tests alternative autoloader (PHP 8.1)	9s
PHPUnit (PHP 8.3)	2m 47s
Tests alternative autoloader (PHP 8.2)	12s
PHPUnit (PHP 8.4)	2m 46s
Tests alternative autoloader (PHP 8.3)	14s
Windows-Tests with PHP 7.1	1m 21s
Windows-Tests with PHP 7.2	1m 4s
Tests alternative autoloader (PHP 8.4)	8s
Windows-Tests with PHP 7.3	1m 6s
Windows-Tests with PHP 7.4	1m 5s
Windows-Tests with PHP 8.0	56s
Windows-Tests with PHP 8.1	57s
Windows-Tests with PHP 8.2	1m 8s
Windows-Tests with PHP 8.3	1m 3s
Windows-Tests with PHP 8.4	1m 7s
	38m 38s

Provide feedback