DEP Increase minimum version of silverstripe/framework #480

Job	Run time
CI / Generate matrix	13s
CI / Context	1s
CI / 8.1 prf-low mysql57 phpunit all	1m 24s
CI / 8.2 mariadb phpunit all	1m 52s
CI / Check governance	0s
CI / 8.3 mysql80 phpunit all	1m 50s
CI / 8.1 mysql57 phplinting	1m 53s
CI / 8.1 mysql57 endtoend root	2m 25s
CI / 8.3 mysql80 endtoend root	3m 32s
CI / 8.1 mysql57 js	3m 47s
CI / Dispatch tag patch release	0s
	16m 57s

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