错误信息：
Note: meta is pinned to version 1.12.0 by flutter from the flutter SDK.
See https://dart.dev/go/sdk-version-pinning for details.
Because analyzer >=6.5.1 depends on meta ^1.15.0 and analyzer >=6.5.0 <6.5.1 depends on meta ^1.14.0, analyzer >=6.5.0 requires meta ^1.14.0.
And because freezed >=2.5.3 <3.0.0-0.0.dev depends on analyzer ^6.5.0 and every version of flutter from sdk depends on meta 1.12.0, freezed >=2.5.3 <3.0.0-0.0.dev is incompatible with flutter from sdk.
So, because pulltorefresh depends on both flutter from sdk and freezed ^2.5.3, version solving failed.
解决方法：
在 pubspec.yaml 覆写依赖。
pubspec.yaml
dependency_overrides:
meta: ^1.14.0
