Prepare for 4.3.1 release #580

Job	Run time
CI test (make validate)	32s
Code coverage (codecov)	0s
Integration tests (8.2, main)	6m 16s
Integration tests (8.2, MOODLE_403_STABLE)	6m 6s
Build moodle-plugin-ci.phar	37s
Integration tests (8.2, MOODLE_402_STABLE)	5m 46s
Integration tests (8.1, MOODLE_401_STABLE)	6m 51s
Integration tests (8.0, MOODLE_400_STABLE)	6m 26s
Integration tests (8.0, MOODLE_311_STABLE)	5m 59s
Integration tests (7.4, MOODLE_39_STABLE)	5m 42s
Integration tests (PHAR) (8.2, main)	6m 31s
Integration tests (PHAR) (8.1, MOODLE_403_STABLE)	5m 44s
Integration tests (PHAR) (8.0, MOODLE_401_STABLE)	6m 32s
Integration tests (PHAR) (7.4, MOODLE_400_STABLE)	5m 57s
	1h 8m 59s

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