Migrate to Poe the Poet and Ruff for checks

As we use Poetry for virtual environment management, we don't require
most of Nox's functionality. Poe the Poet runs more quickly, and
requires fewer lines of configuration. Ruff provides a single tool
which can replace flake8, pylint, pyupgrade, and isort, whilst
running more quickly.

.github/CONTRIBUTING.md

@@ -51,7 +51,7 @@ After cloning the repository, you can implement your changes as follows:
 1. Install the project and its dependencies into an isolated virtual environment
    with `poetry install`.
 2. Before making your changes, run the linters and test suite with
-   `poetry run nox`, and ensure they pass. This checks your development
+   `poetry run poe check`, and ensure they pass. This checks your development
    environment is correctly configured, and there aren't outstanding issues
    before you start coding. If they don't pass, you can open a GitHub issue for
    help debugging.
@@ -62,7 +62,7 @@ After cloning the repository, you can implement your changes as follows:
    tests to prevent future regressions.
 6. Ensure you've updated any docstrings or documentation files (including
    `README.md`) which are affected by your change.
-7. Run the linters and test suite again with `poetry run nox`, and fix any
+7. Run the linters and test suite again with `poetry run poe check`, and fix any
    problems.
 8. Commit your changes, following [these guidelines][commit guidelines] for your
    commit messages.

.github/workflows/ci.yml

@@ -6,8 +6,8 @@ on:
   pull_request:
 
 jobs:
-  nox:
-    name: Run Nox
+  checks:
+    name: Run checks
     runs-on: ubuntu-latest
     strategy:
       matrix:
@@ -29,8 +29,8 @@ jobs:
           python3 -m pip install coverage poetry
           poetry install
 
-      - name: Run Nox
-        run: poetry run nox
+      - name: Run checks
+        run: poetry run poe check
 
       - name: Create XML coverage report
         run: poetry run coverage xml

.gitignore

@@ -2,7 +2,6 @@
 .ipynb_checkpoints/
 /.coverage
 /.mypy_cache/
-/.nox/
 /build/
 /coverage.xml
 /dist/