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

action.yml

@@ -11,9 +11,12 @@ inputs:
     required: false
     default: ${{ github.workspace }}
   version:
-    description: "The version of Ruff to use, e.g., `0.6.0` Defaults to the latest version."
+    description: "The version of Ruff to use, e.g., `0.6.0` Defaults to the version in pyproject.toml or 'latest'."
+    required: false
+    default: ""
+  version-file:
+    description: "Path to a pyproject.toml or requirements.txt file to read the version from."
     required: false
-    default: "latest"
   checksum:
     description: "The checksum of the ruff version to install"
     required: false