Adjust filter plugin validation requirements to comply with Moodle 4.5 #709

Job	Run time
CI test (make validate)	54s
Code coverage (codecov)	56s
Integration tests (8.3, main, true)	6m 52s
Build moodle-plugin-ci.phar	24s
Integration tests (8.3, MOODLE_405_STABLE, true)	6m 44s
Integration tests (8.3, MOODLE_404_STABLE, true)	6m 23s
Integration tests (8.2, MOODLE_403_STABLE, true)	6m 19s
Integration tests (8.2, MOODLE_402_STABLE, true)	6m 3s
Integration tests (8.1, MOODLE_401_STABLE, true)	6m 53s
Integration tests (8.0, MOODLE_400_STABLE)	5m 38s
Integration tests (8.0, MOODLE_311_STABLE)	5m 2s
Integration tests (7.4, MOODLE_39_STABLE)	5m 18s
SelfUpdate tests (PHAR) (8.3)	32s
Integration tests (PHAR) (8.3, main, true)	6m 0s
SelfUpdate tests (PHAR) (8.2)	31s
Integration tests (PHAR) (8.3, MOODLE_405_STABLE, true)	6m 5s
SelfUpdate tests (PHAR) (8.1)	18s
Integration tests (PHAR) (8.3, MOODLE_404_STABLE, true)	5m 50s
SelfUpdate tests (PHAR) (8.0)	24s
Integration tests (PHAR) (8.2, MOODLE_403_STABLE, true)	6m 14s
SelfUpdate tests (PHAR) (7.4)	9s
Integration tests (PHAR) (8.1, MOODLE_402_STABLE, true)	5m 48s
Integration tests (PHAR) (8.0, MOODLE_401_STABLE, true)	6m 21s
Integration tests (PHAR) (7.4, MOODLE_400_STABLE)	4m 55s
	1h 40m 33s

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