chore: bump version to 2.23.2

[ketor]

Release scope

Patch release for merged PR #352 (feat(lmcache): add rank-local RDMA rail affinity). The unreleased range contains Python LMCache connector integration, tests, and documentation only; no src/ C++ datapath change.

Version sources

Updated all six static version positions required by the release contract:

• VERSION
• integration/common/pyproject.toml project version
• integration/lmcache/pyproject.toml project version and dfkv-common pin
• integration/vllm/pyproject.toml project version and dfkv-common pin

Validation

• RDMA-enabled Release build succeeded
• CTest: 787/787 completed, 0 failures (environment-gated tests skipped)
• dfkv_server, dfkvctl, dfkv_mds, and libdfkv.so: 2.23.2
• built dfkv_common-2.23.2, dfkv_connector-2.23.2, and dfkv_vllm-2.23.2 wheels
• feature PR feat(lmcache): add rank-local RDMA rail affinity #352 CI run 32225837457 attempt 4: all eight jobs successful
• git diff --check passed