chore: ignore cls type annotations on linter

[davidcavazos]

Description

We're currently ignoring ANN101 which is for self type annotations on methods. We should probably also ignore ANN102 which is for cls type annotations on @classmethod. It's basically the same as self, but instead of being a reference to the object, it's a reference to the class.

The Self type annotation is redundant (the same class name) and does not give any additional information. Even in the official Python type hints documentation, they don't annotate self, for example here. Even though they don't explicitly mention the recommended style, they do mention that the Self type is usually used for return types of the same class, rather than for annotating self or cls.

Checklist

• I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• README is updated to include all relevant information
• Tests pass: nox -s py-3.9 (see Test Environment Setup)
• Lint pass: nox -s lint (see Test Environment Setup)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

[iennae]

Thanks @davidcavazos