intl should be reverted to v0.17.0 until Flutter stable supports v0.18.0

[absar]

Describe the bug
We cannot use rrule 0.2.11 or 0.2.12 with Flutter stable 3.7.7, since Flutter usually pins the dependency on intl currently it is 0.17. Hence ideally this package and any other packages should follow flutter.
The issue: Because App depends on flutter_localizations from sdk which depends on intl 0.17.0, intl 0.17.0 is required. So, because App depends on intl ^0.18.0, version solving failed, the 0.18.0 in error is due to rrule using intl 0.18.0
Unfortunately we cannot use rrule 0.2.10 since rrule 0.2.12 has a bug fix.

Environment:

• Package version: rrule: ^0.2.12
• Flutter: Channel stable, 3.7.7

[JonasWanke]

The new release v0.2.13 widened the intl dependency to >=0.17.0 <0.19.0 so that rrule should work fine with both Flutter stable and beta