Advance mitmproxy pin to unblock security dependency sync

[ibrahim halatci (ihalatci)]

Summary

Advance the Citus mitmproxy fork pin to the commit from citusdata/mitmproxy#5 in both regression-test Pipfiles and their lock metadata.

The updated fork adds cap support for:

• cryptography==50.0.0
• h2==4.4.1
• tornado==6.5.8
• OpenSSL 4 unsupported-protocol probe compatibility

This is intentionally a metadata-only minimal change: current package versions remain pinned. Once this PR merges, run dependency-security-sync in citusdata/the-process to generate the actual patched Citus lockfiles and test-image requirements as coordinated PRs.

Validation

The current .github/scripts/security_sync.py from citusdata/the-process was run against all 14 current Citus Dependabot alerts in WSL Ubuntu 22.04 with Python 3.12, resolving the unpublished fork commit locally through a temporary Git URL rewrite.

• tornado, h2, and cryptography all reported ['applied', 'applied']
• All alerts were addressed with blocked=[]
• Paired generated lockfiles were identical
• pipenv verify succeeded
• Full generated consumer development dependencies installed; pip check succeeded
• mitmdump --version started successfully with OpenSSL 4.0.1
• The fork's targeted seven-file suite passed with baseline and exact patched dependencies: 199 passed and 1 platform skip in each run

No workflow code, package versions, tests, or build tools are changed here.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.73%. Comparing base (5eaf894) to head (e4a61f6).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8840      +/-   ##
==========================================
- Coverage   88.73%   88.73%   -0.01%     
==========================================
  Files         289      289              
  Lines       65012    65012              
  Branches     8203     8204       +1     
==========================================
- Hits        57690    57688       -2     
- Misses       4952     4954       +2     
  Partials     2370     2370              

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[ibrahim halatci (ihalatci)]

Superseded by #8841, which includes this mitmproxy pin change together with the generated security dependency updates. The coordinated image requirements are in citusdata/the-process#249; that PR should merge first so its post-merge workflow advances the Citus PR to released images. Closing only this duplicate pin-only PR.