bump 3.12 to 3.13 in readme · Instagram/LibCST@7987432

Unable to create clippy annotations! Reason: HttpError: Resource not accessible by integration

The following actions uses node12 which is deprecated and will be forced to run on node16: actions-rs/cargo@v1, actions-rs/clippy-check@v1. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/

The following actions use a deprecated Node.js version and will be forced to run on node20: actions-rs/cargo@v1, actions-rs/clippy-check@v1. For more info: https://github.blog/changelog/2024-03-07-github-actions-all-actions-will-run-on-node20-instead-of-node16-by-default/

It seems that this Action is executed from the forked repository.

GitHub Actions are not allowed to create Check annotations, when executed for a forked repos. See https://github.com/actions-rs/clippy-check/issues/2 for details.

unused imports: `DeflatedAsynchronous as Asynchronous` and `DeflatedFormattedStringText as FormattedStringText`

unused import: `DeflatedImportStar as ImportStar`