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

package-lock.json

@@ -12,7 +12,8 @@
         "@actions/core": "^1.11.1",
         "@actions/exec": "^1.1.1",
         "@actions/github": "^6.0.0",
-        "@actions/tool-cache": "^2.0.1"
+        "@actions/tool-cache": "^2.0.1",
+        "toml": "^3.0.0"
       },
       "devDependencies": {
         "@biomejs/biome": "1.9.4",
@@ -453,6 +454,11 @@
         "semver": "bin/semver.js"
       }
     },
+    "node_modules/toml": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/toml/-/toml-3.0.0.tgz",
+      "integrity": "sha512-y/mWCZinnvxjTKYhJ+pYxwD0mRLVvOtdS2Awbgxln6iEnt4rk0yBxeSBHkGJcPucRiG0e55mwWp+g/05rsrd6w=="
+    },
     "node_modules/tunnel": {
       "version": "0.0.6",
       "resolved": "https://registry.npmjs.org/tunnel/-/tunnel-0.0.6.tgz",