General: update our PHP version requirements to PHP 7.0 #66769

Job	Run time
Determine tests matrix	1m 10s
E2E: Build jetpack-boost	3m 51s
E2E: Build jetpack-core	4m 2s
E2E: Build jetpack-search	3m 54s
E2E: Build jetpack-social	3m 34s
E2E: Build jetpack-sync	3m 50s
E2E: Build jetpack-videopress	3m 12s
Jetpack connection e2e tests	6m 25s
Jetpack pre-connection e2e tests	3m 29s
Jetpack post-connection e2e tests	5m 39s
Jetpack sync e2e tests	5m 48s
Jetpack Boost - Base e2e tests	5m 1s
Jetpack Boost - Modules e2e tests	4m 43s
Jetpack Boost - Critical CSS e2e tests	4m 17s
Search e2e tests	4m 59s
VideoPress e2e tests	3m 13s
Social e2e tests	3m 48s
Slack notification	1m 4s
Test report	4s
	1h 12m 3s

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