Add "phpstan/extension-installer" to allowed plugins #91

Job	Run time
PHP 8.1, ubuntu-latest, prefer-lowest	23s
PHP 8.1, ubuntu-latest, prefer-stable	14s
PHP 8.1, macos-latest, prefer-lowest	1m 8s
PHP 8.1, macos-latest, prefer-stable	1m 13s
PHP 8.1, windows-latest, prefer-lowest	33s
PHP 8.1, windows-latest, prefer-stable	32s
PHP 8.2, ubuntu-latest, prefer-lowest	12s
PHP 8.2, ubuntu-latest, prefer-stable	16s
PHP 8.2, macos-latest, prefer-lowest	1m 26s
PHP 8.2, macos-latest, prefer-stable	1m 11s
PHP 8.2, windows-latest, prefer-lowest	31s
PHP 8.2, windows-latest, prefer-stable	33s
PHP 8.3, ubuntu-latest, prefer-lowest	17s
PHP 8.3, ubuntu-latest, prefer-stable	13s
PHP 8.3, macos-latest, prefer-lowest	1m 15s
PHP 8.3, macos-latest, prefer-stable	1m 7s
PHP 8.3, windows-latest, prefer-lowest	30s
PHP 8.3, windows-latest, prefer-stable	38s
PHP 8.4, ubuntu-latest, prefer-lowest	10s
PHP 8.4, ubuntu-latest, prefer-stable	13s
PHP 8.4, macos-latest, prefer-lowest	1m 33s
PHP 8.4, macos-latest, prefer-stable	1m 21s
PHP 8.4, windows-latest, prefer-lowest	40s
PHP 8.4, windows-latest, prefer-stable	30s
	16m 39s

Provide feedback