chore: remove Python 3.7 and 3.8 from project classifiers

The project requires Python >=3.9 (requires-python), so the 3.7 and
3.8 classifiers are misleading.

Closes #1497

Co-Authored-By: AtomCode (deepseek-v4-flash) <noreply@atomgit.com>

Author: ChenfromChina123

pyproject.toml

@@ -13,8 +13,6 @@ classifiers = [
     "Operating System :: OS Independent",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.7",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",