Feature: 使用 importlib.metadata 替换 pkg_resources

[A-kirami]

importlib.metadata 是一个提供对已安装包的元数据访问的库。这个库部分建立在 Python 的导入系统上，旨在取代 pkg_resources 的 entry point API 和 metadata API 中的类似功能。 通过和 Python 3.7 或更高版本中的 importlib.resources 一同使用（对于旧版本的 Python 则作为 importlib_resources 向后移植），这可以消除对使用较旧且较为低效的 pkg_resources 包的需要。

移除对setuptools的依赖，移除变量nonebot.VERSION支持，自行使用packaging.version.parse

[codecov]

Codecov Report

Merging #1388 (83855c7) into master (0bc8a39) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1388      +/-   ##
==========================================
- Coverage   85.91%   85.90%   -0.01%     
==========================================
  Files          41       41              
  Lines        3230     3228       -2     
==========================================
- Hits         2775     2773       -2     
  Misses        455      455              

Flag	Coverage Δ
unittests	85.90% <100.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
nonebot/__init__.py	100.00% <100.00%> (ø)

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[github-actions]

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