request: Migrate away from discontinued `pubspec` package

[spydon]

Is there an existing feature request for this?

• [X] I have searched the existing issues.

Command

No response

Description

We should migrate away from the discontinued pubspec package and use pubspec_parse or pubspec_manager.

Reasoning

Since there are a few bugs in in the pubspec package we should move away from it, the other packages also have more features.

Additional context and comments

No response