fix: Implemented graceful shutdown

[Isawan]

Wait until all in-flight requests are responded to before shutdown

[codecov]

Codecov Report

Attention: Patch coverage is 96.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.59%. Comparing base (91cc7a3) to head (c2ce5c1).

❗ Current head c2ce5c1 differs from pull request most recent head c0527a3

Please upload reports for the commit c0527a3 to get more accurate results.

Files	Patch %	Lines
src/lib.rs	96.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #394      +/-   ##
==========================================
- Coverage   81.62%   81.59%   -0.03%     
==========================================
  Files          19       19              
  Lines        1317     1315       -2     
==========================================
- Hits         1075     1073       -2     
  Misses        242      242              

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