Improve CI (#38) #25

Job	Run time
Tests / Fetch supported versions	4s
Tests / Static analysis	28s
Tests / Up to date versions	28s
Tests / Late migration - Symfony	29s
Tests / Up to date versions - Special case - Symfony 5.4	26s
Tests / Late migration - PHP	16s
Tests / Bare minimum - Special case - Symfony 5.4	19s
Tests / Bare minimum	16s
Tests / Nightly - PHP - With highest supported Symfony versions	24s
Tests / Nightly - Symfony - With highest supported PHP version	17s
Tests / Nightly - PHP - With lowest supported Symfony versions	18s
Tests / Nightly - Symfony - With lowest supported PHP version	19s
	4m 4s

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