chore: add .gitattributes to standardize the default end-of-file line

[Skyenought]

What type of PR is this?

chore

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• This PR title match the format: <type>(optional scope): <description>
• The description of this PR title is user-oriented and clear enough for others to understand.

(Optional) Translate the PR title into Chinese.

(Optional) More detailed description for this PR(en: English/zh: Chinese).

zh(optional): 添加 .gitattributes 用于在使用 git 提交文件时统一默认的文件结尾行
防止出现类似 .sh 文件在 win 下无法执行或 执行 gofumpt 时因为更改换行符导致显示大量文件被改动等情况

(Optional) Which issue(s) this PR fixes:

gofiber/fiber#2286

(Optional) The PR that updates user documentation:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (e02c162) 81.86% compared to head (5b3bede) 81.88%.

❗ Current head 5b3bede differs from pull request most recent head 6886a7e. Consider uploading reports for the commit 6886a7e to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #981      +/-   ##
===========================================
+ Coverage    81.86%   81.88%   +0.02%     
===========================================
  Files           98       98              
  Lines         9932     9932              
===========================================
+ Hits          8131     8133       +2     
+ Misses        1311     1310       -1     
+ Partials       490      489       -1     

see 1 file with indirect coverage changes

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