fix: replace deprecated pkg_resources with importlib.resources (#116)

[DhruvrajSinhZala24]

Fixes #116

Problem

Atarashi fails with ModuleNotFoundError: No module named 'pkg_resources' when running on Python 3.10+ environments where setuptools >= 80 is installed. This is particularly prevalent in modern distributions like Ubuntu 22.04+ with Python 3.12.

Reproduction Steps

1. Initialize a Python 3.12 environment.
2. Ensure setuptools >= 80.0.0 is installed.
3. Run any atarashi command (e.g., atarashi -h) or try to import the evaluator (from atarashi.evaluator.evaluator import evaluate).
4. Result: ModuleNotFoundError: No module named 'pkg_resources'.

Root Cause

The pkg_resources API is part of setuptools but has been deprecated for several years and is officially removed from the default installation in recent versions (v80+). Atarashi was using pkg_resources.resource_filename to locate internal license and data files, which is no longer a reliable or standard practice in modern Python packaging.

Fix Implemented

I have migrated the resource loading logic in atarashi/evaluator/evaluator.py to use importlib.resources, which is the standard library replacement for pkg_resources.

• Replaced pkg_resources.resource_filename with importlib.resources.files.
• Added a graceful fallback to the importlib_resources backport (which is already a project dependency) for maximum compatibility.
• This fix ensures that the project does not depend on setuptools at runtime, aligning with current PyPA recommendations.

Testing Performed

• Verified that atarashi -h and evaluator imports work perfectly in an environment with setuptools 80.10.2 and Python 3.13.
• Verified that all default resource paths for processedLicenses.csv and Ngram_keywords.json are resolved correctly.