v3.3.0 has dependency conflict with flutter web

oauth2_client 3.3.0 doesn't work with flutter web.

oauth2_client depends on meta ^1.12.0
flutter_web_plugins depends on meta 1.11.0 exactly


error log:
```
Because oauth2_client >=3.3.0 depends on meta ^1.12.0 and every version of flutter_web_plugins from sdk depends on meta 1.11.0, oauth2_client >=3.3.0 is incompatible with flutter_web_plugins from sdk.
```

Thanks