Consider rolling meta back to ^1.8.0

[jpeiffer]

The package flutter_test is pegged to meta: 1.8.0. The dependency on meta: ^1.9.0 means that any application that utilizes this package cannot easily utilize flutter_test when utilizing the latest stable version of Flutter, which is highly unfortunate for all Flutter applications.

If this depended on ^1.8.0 then internally it can use ^1.9.0 without breaking Flutter applications with unit tests.

[renggli]

From a practical standpoint I am unable to test with all possible old packages and SDK dependencies. New releases are always published with the latest stable dependencies. Consider sticking with an older version of this package until your dependencies have caught up.