Fix GitHub Actions and pyproject.toml configuration issues

- Updated actions/upload-artifact from deprecated v3 to v4
- Fixed pyproject.toml license format from "MIT" to {text = "MIT"}
- Package configuration now validates successfully

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

pyproject.toml

@@ -6,7 +6,7 @@ build-backend = "setuptools.build_meta"
 name = "wikijs-python-sdk"
 description = "A professional Python SDK for Wiki.js API integration"
 authors = [{name = "Wiki.js SDK Contributors", email = "contact@wikijs-sdk.dev"}]
-license = "MIT"
+license = {text = "MIT"}
 readme = "README.md"
 requires-python = ">=3.8"
 classifiers = [