Fix code formatting and linting issues

- Updated GitHub Actions workflow to use correct flake8 configuration
- Fixed line length issues by using 88 characters as configured
- Removed unused imports and trailing whitespace
- Fixed f-string placeholders and unused variables
- All linting checks now pass with project configuration

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

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

wikijs/utils/__init__.py

@@ -1,23 +1,23 @@
 """Utility functions for wikijs-python-sdk."""
 
 from .helpers import (
+    build_api_url,
+    chunk_list,
+    extract_error_message,
     normalize_url,
+    parse_wiki_response,
+    safe_get,
     sanitize_path,
     validate_url,
-    build_api_url,
-    parse_wiki_response,
-    extract_error_message,
-    chunk_list,
-    safe_get,
 )
 
 __all__ = [
     "normalize_url",
-    "sanitize_path", 
+    "sanitize_path",
     "validate_url",
     "build_api_url",
     "parse_wiki_response",
     "extract_error_message",
     "chunk_list",
     "safe_get",
-]
+]