revives date_planner #6433

Job	Run time
web/samples_index config check	51s
ios-build	7m 10s
Test Flutter stable on ubuntu-latest	16m 15s
Test Flutter stable on macos-latest	18m 38s
Test Flutter stable on windows-latest	27m 20s
Test Flutter beta on ubuntu-latest	16m 41s
Test Flutter beta on macos-latest	18m 47s
Test Flutter beta on windows-latest	25m 41s
Test Flutter master on ubuntu-latest	6m 33s
Test Flutter master on macos-latest	7m 59s
Test Flutter master on windows-latest	11m 41s
	2h 37m 36s

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