Bump phpstan to 1.12.x #1418

Job	Run time
Windows - PHP 8.1 & SQL Server	3m 50s
Coding Standard & Static Analysis	32s
testsuite (8.1, sqlite)	36s
testsuite (8.1, mysql)	44s
testsuite (8.4, pgsql)	54s
testsuite (8.1, pgsql)	45s
testsuite (8.4, sqlite)	30s
testsuite (8.4, mysql)	54s
testsuite (8.1, sqlite, prefer-lowest)	27s
testsuite (8.2, mysql)	55s
	10m 7s

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