Update intl to 18.1

[MissingDataDev]

No description provided.

[svnty]

Because date_time_picker >=2.0.0 depends on intl ^0.17.0 and every version of flutter_localizations from sdk depends on intl 0.18.1, date_time_picker >=2.0.0 is incompatible with flutter_localizations from sdk.
And because device_preview >=0.7.0 depends on flutter_localizations from sdk and device_preview <0.7.0 doesn't support null safety, date_time_picker >=2.0.0 is incompatible with device_preview.
So, because medicamina_ui depends on both date_time_picker ^2.1.0 and device_preview any, version solving failed.

[basilmariano]

can we merge this pls