fix(deps): bump python-multipart, cryptography, pyjwt to clear HIGH alerts (#4398)

Resolves a fresh batch of Dependabot alerts (disclosed 2026-06-15/16,
after PR #4376 merged) across the fetch, git, and time server lockfiles:

- python-multipart 0.0.27 -> 0.0.32 (CVE-2026-53539 HIGH querystring DoS,
  plus CVE-2026-53537/53538/53540 parameter smuggling / buffering)
- cryptography     48.0.0  -> 49.0.0 (GHSA-537c-gmf6-5ccf HIGH, vulnerable
  OpenSSL statically linked in wheels < 48.0.1)
- pyjwt            2.12.1  -> 2.13.0 (HIGH + medium JWT advisories)

All three are transitive deps; lockfiles only. Diff scoped to exactly
these 9 version bumps with no other resolution churn. git server tests
unchanged vs base (43 passed; 37 pre-existing Windows tempdir errors).

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: olaservo