pep8 and code details in weyl_characters.py

[fchapoton]

📚 Description

Partial pep8 cleanup of the wile weyl_characters.py

also simplifying some dictionary constructions

and renaming adams_operation to adams_operator

📝 Checklist

• The title is concise, informative, and self-explanatory.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[github-actions]

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Built with commit: e33815f

[dcoudert]

LGTM.

At first I was surprised by the name change of method _adams_operation_helper, and then I saw the line adams_operation = adams_operator.