fix(api): fix a bug with api_spec retrieval

[alexander-zuev]

Description

Fixed a big with an incorrect path to the api_spec

Type of Change

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

Checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• New and existing unit tests pass locally with my changes

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 11.11111% with 16 lines in your changes missing coverage. Please review.

Project coverage is 84.6%. Comparing base (141e958) to head (f235c0a).

Files with missing lines	Patch %	Lines
supabase_mcp/services/api/spec_manager.py	11.1%	16 Missing ⚠️

@@           Coverage Diff           @@
##            main     #43     +/-   ##
=======================================
+ Coverage   84.1%   84.6%   +0.5%     
=======================================
  Files         24      24             
  Lines       1372    1375      +3     
=======================================
+ Hits        1154    1164     +10     
+ Misses       218     211      -7     

Files with missing lines	Coverage Δ
supabase_mcp/services/api/spec_manager.py	69.1% <11.1%> (+5.5%)	⬆️

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.