Bump express from 4.19.2 to 4.21.0 (#364) #633

Job	Run time
CI / Context	1s
CI / Generate matrix	21s
CI / Check governance	1s
CI / 8.1 prf-low mysql57 phpunit all	2m 1s
CI / 8.2 mariadb phpunit all	1m 55s
CI / 8.3 mysql80 phpunit all	2m 30s
CI / 8.3 mysql84 phpunit all	2m 3s
CI / 8.1 mysql57 phplinting	1m 49s
CI / 8.1 mysql57 endtoend root job1	6m 19s
CI / 8.3 mysql80 endtoend root job1	6m 33s
CI / 8.1 mysql57 endtoend root job2	5m 54s
CI / 8.3 mysql80 endtoend root job2	6m 7s
CI / 8.1 mysql57 js	5m 44s
CI / Dispatch tag patch release	4s
	41m 22s

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