Replace flake8 + black + isort with ruff (#411)

ruff is a single tool and acts as a drop-in replacement for all these tools.
It's config is in one place, in pyproject.toml. And it's blazing fast!

This commit also removes tox and depends on GitHub actions for multi-env
testing.

Fixes #410

.pre-commit-config.yaml

@@ -1,23 +1,10 @@
 repos:
-  - repo: https://github.com/psf/black
-    rev: 24.2.0
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    # Ruff version.
+    rev: v0.4.3
     hooks:
-      - id: black
-        language_version: python3
-
-  - repo: [email protected]:PyCQA/autoflake.git
-    rev: v2.3.1
-    hooks:
-      - id: autoflake
-        args:
-          [
-            "--in-place",
-            "--remove-all-unused-imports",
-            "--ignore-init-module-imports",
-          ]
-
-  - repo: https://github.com/pycqa/isort
-    rev: 5.13.2
-    hooks:
-      - id: isort
-        args: ["--profile", "black", "--filter-files", "--quiet"]
+      # Run the linter.
+      - id: ruff
+        args: [ --fix ]
+      # Run the formatter.
+      - id: ruff-format

docs_src/guides/domain-definition/009.py

@@ -7,7 +7,7 @@
 
 class EmailValidator:
     def __init__(self):
-        self.error = f"Invalid email address"
+        self.error = "Invalid email address"
 
     def __call__(self, value):
         """Business rules of Email address"""