deps: update litellm requirement from >=1.85.0 to >=1.88.1 in /backend

[dependabot]

Updates the requirements on litellm to permit the latest version.

Release notes

Sourced from litellm's releases.

v1.88.1

Verify Docker Image Signature

All LiteLLM Docker images are signed with cosign. Every release is signed with the same key introduced in commit 0112e53.

Verify using the pinned commit hash (recommended):

A commit hash is cryptographically immutable, so this is the strongest way to ensure you are using the original signing key:

cosign verify \
  --key https://raw.githubusercontent.com/BerriAI/litellm/0112e53046018d726492c814b3644b7d376029d0/cosign.pub \
  ghcr.io/berriai/litellm:v1.88.1

Verify using the release tag (convenience):

Tags are protected in this repository and resolve to the same key. This option is easier to read but relies on tag protection rules:

cosign verify \
  --key https://raw.githubusercontent.com/BerriAI/litellm/v1.88.1/cosign.pub \
  ghcr.io/berriai/litellm:v1.88.1

Expected output:

The following checks were performed on each of these signatures:
  - The cosign claims were validated
  - The signatures were verified against the specified public key

---

What's Changed

• build(deps): bump pyjwt to 2.13.0 and ws override to 8.20.1 (1.88.x) by @​yuneng-berri in BerriAI/litellm#29987
• chore(release): bump version to 1.88.1 by @​yuneng-berri in BerriAI/litellm#29989

Full Changelog: BerriAI/litellm@v1.88.0...v1.88.1

Commits

• 9c117a5 Merge pull request #29989 from BerriAI/litellm_bump_version_1_88_1
• b577372 chore(release): bump version to 1.88.1
• f685f2f Merge pull request #29987 from BerriAI/litellm_deps_pyjwt_ws_backport_1_88_x
• aa2deee build(deps): bump pyjwt to 2.13.0 and ws override to 8.20.1
• bde16ff test(proxy): patch utils.get_server_root_path in passthrough auth tests
• 3d00874 fix(proxy): match passthrough registry routes bare-to-bare with SERVER_ROOT_PATH
• 67428bd Merge pull request #29639 from BerriAI/litellm_ghsa_q775_defaults_rc188
• c5d214c fix(key_generate): harden GHSA-q775 session-token exemption against default_k...
• c2a0a6a Merge pull request #29637 from BerriAI/litellm_cherrypick_1_88_0_rc3
• 26e9689 fix(key_generate): exempt UI/CLI session tokens from the budget ceiling for t...
• Additional commits viewable in compare view

[dependabot]

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