Default to ruff-version from pyproject.toml (#30)

Closes: #9 

Changes the default behavior to:

- Search for a pyproject.toml in the repo root
- Search in project.dependencies and dependency-groups.dev for ruff
- If none is found use latest

Support for requirements.txt files can be added later

__tests__/fixtures/python-project/pyproject.toml

@@ -5,7 +5,7 @@ description = "Add your description here"
 readme = "README.md"
 requires-python = ">=3.12"
 dependencies = [
-    "ruff>=0.6.2",
+    "ruff==0.6.2",
 ]
 
 [build-system]