Mark more method with phpstan-impure #307

Job	Run time
Platform test (7.4)	2m 50s
Platform test (8.3)	2m 48s
Platform test (8.1)	2m 35s
Platform test (8.2)	2m 44s
Platform test (8.4)	2m 57s
Platform test (8.0)	3m 6s
Platform test (8.3, doctrine/orm:^3.0 doctrine/dbal:^4.0 carbonphp/carbon-doctrine-types:^3 gedmo...	2m 36s
Platform test (8.2, doctrine/orm:^3.0 doctrine/dbal:^4.0 carbonphp/carbon-doctrine-types:^3 gedmo...	2m 38s
Platform test (8.4, doctrine/orm:^3.0 doctrine/dbal:^4.0 carbonphp/carbon-doctrine-types:^3 gedmo...	2m 24s
Platform test (8.1, doctrine/orm:^3.0 doctrine/dbal:^4.0 carbonphp/carbon-doctrine-types:^3 gedmo...	2m 18s
	26m 56s

Provide feedback