Add va_end call

[azkrishpy]

Issue #, and/or reason for changes (REQUIRED):

Description of changes:
Trivial bugfix: Added corresponding va_end() call for args before return.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.18%. Comparing base (192ab0d) to head (45016f9).

Files with missing lines	Patch %	Lines
source/byte_buf.c	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1228      +/-   ##
==========================================
- Coverage   84.21%   84.18%   -0.03%     
==========================================
  Files          58       58              
  Lines        6093     6095       +2     
==========================================
  Hits         5131     5131              
- Misses        962      964       +2     

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