optimize asyncio operations

bring back resources counter

Modernize codebase to Python 3.11+ with optional performance enhancements
- Bump minimum Python version to 3.11
- Make uvloop (non-Windows) and winloop (Windows) optional dependencies
- Add signal handlers (SIGINT, SIGTERM) for graceful shutdown
- Update setup.py to use README.md with Markdown support

add README.md

code optimization

Added tag v3.0.2 for changeset 646f7d743ced

v3.0.2

Added tag v3.0.2 for changeset 78b87885a0d1

Python 3.6 is a minimum requirement

Added tag v3.0.1 for changeset c3539aeca9bc

change repository URL in README.rst to sourcehut

Added tag v3.0.0 for changeset 3eedda7bba5f

fix wrong setup.py

Added tag v3.0.0 for changeset d41ba185ad68

change URL to sourcehut

Added tag v3.0.0 for changeset 2009d691434f

use f-string where applicable

black reformat

insert package dir to sys.path to simplify import

Import package name as setup.py doesn't work with relative path.