update requests to scheduler

[KentonParton]

Description

When adding distributed tracing such as open telemetry, it requires the ability to modify headers. This PR allows that for requests between swiple-api and swiple-scheduler

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have performed a self-review of my own code
• All GitHub workflows have passed
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 41.66667% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.21%. Comparing base (5da9a9a) to head (d092a1f).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
backend/app/api/api_v1/endpoints/schedule.py	12.50%	7 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##             main      #80      +/-   ##
==========================================
- Coverage   67.31%   67.21%   -0.10%     
==========================================
  Files          71       71              
  Lines        3121     3133      +12     
==========================================
+ Hits         2101     2106       +5     
- Misses       1020     1027       +7     

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