update CONTRIBUTING

CONTRIBUTING.md

@@ -107,18 +107,14 @@ poetry install
 
 ### Style Guidelines
 
-We use [Black](https://black.readthedocs.io/en/stable/index.html) and `flake8` to automatically
-lint the code and enforce style requirements as part of the CI pipeline. You can run these style
-tests yourself locally by running `make check-style` (to check for violations of the `flake8` rules)
-and `make check-format` (to see if `black` would reformat the code) in the top-level directory of
-the repository. If you aren't presented with any errors, then that means your code is good enough
-for the linter (`flake8`) and formatter (`black`). If `make check-format` fails, it will present
-you with a diff, which you can resolve by running `make format`. Black is very opinionated, but
-saves a lot of time by removing the need for style nitpicks in PR review. We only deviate from its
-default behavior in one category: we choose to use a line length of 100 rather than the Black
-default of 88 (this is configured in the [`pyproject.toml`](pyproject.toml) file). As for `flake8`,
-we ignore a couple of its rules (all for good reasons), and the specific configuration can be
-found in the [`.flake8`](.flake8) file.
+We use [ruff]() to enforce lint and formatting requireements as part of CI. You can run these
+tests yourself locally by running `make check-style` (to check for violations of the linting rules)
+and `make check-format` (to see if `ruff` would reformat the code) in the top-level directory of
+the repository. If you aren't presented with any errors, then that means your code satisfies all
+the linting and formatting requirements. If `make check-format` fails, it will present you with a
+diff, which you can resolve by running `make format`. The ruff formatter is opinionated, but
+saves a lot of time by removing the need for style nitpicks in PR review. The configuration for
+`ruff` can be found in `pyproject.toml`.
 
 In addition to linting and formatting, we use type hints for all parameters and return values,
 following the [PEP 484 syntax][pep-484]. This is enforced as part of the CI via the command