[TASK] Allow `assertInstanceOf` calls in tests #1965

Job	Run time
PHP Lint (7.2)	26s
PHP Lint (7.3)	23s
PHP Lint (7.4)	18s
PHP Lint (8.0)	12s
PHP Lint (8.1)	14s
PHP Lint (8.2)	38s
PHP Lint (8.3)	24s
PHP Lint (8.4)	17s
Static Analysis (composer:normalize, 8.3)	25s
Static Analysis (php:fixer, 8.3)	33s
Unit tests (7.2)	11s
Static Analysis (php:stan, 8.3)	32s
Unit tests (7.3)	11s
Static Analysis (php:rector, 8.3)	29s
Unit tests (7.4)	17s
Unit tests (8.0)	25s
Unit tests (8.1)	11s
Unit tests (8.2)	22s
Unit tests (8.3)	27s
Unit tests (8.4)	17s
	7m 12s

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