changing the sdk version of a package should not be breaking

[devmil]

Describe the bug
By default dart_apitool considers a change in the SDK version of a package as breaking.
As pub makes sure that those packages are just not considered as an option this can not lead to a situation that breaks an existing codebase.

To Reproduce
Bump SDK version of a package and let dart_apitool compare the new version with the previous one

Actual and Expected behavior
Bumping the SDK version should be a minor change (not breaking)

System info (please complete the following information):

• Output of dart --version
Dart SDK version: 3.5.3 (stable) (Wed Sep 11 16:22:47 2024 +0000) on "macos_arm64"
• dart_apitool version (dart-apitool --version)
  0.18.0

Additional context
See here: Link