chore: bump ngx_multi_upstream_module to 1.3.4

[jarvis9443]

Picks up api7/ngx_multi_upstream_module#22, a use-after-free that crashes the worker.

ngx_http_multi_upstream_connection_close() destroyed c->pool and then called ngx_close_connection(c), which still logs through c->log — and for these upstream connections c->log lives in the pool that was just released. On a debug-enabled build the ngx_log_debug1(..., "reusable connection: %ui") inside ngx_reusable_connection() reads a freed ngx_log_t and hands ngx_write_fd() a garbage descriptor.

It shows up as an intermittent SIGSEGV on APISIX's t/plugin/dubbo-proxy/upstream.t TEST 1 (roughly one run in three locally against 1.3.16, and it took out a CI shard on apache/apisix#13863 once).

[coderabbitai]

Warning

Review limit reached

• Run on-demand review

_{On-demand reviews are free for the next 25 days. After that, they cost $0.25 per reviewed file.}

Or wait 58 minutes for your next included review.

View limit details

Limit details: You’ve used the included review currently available. Your 61 included PR review attempts over the past 7 days set your current allowance at 1 review per hour.

Learn how review limits work.

Review configuration:

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: b0c97281-e55f-4695-91b4-ad3d191f9d0b

📥 Commits

Reviewing files that changed from the base of the PR and between 97b9815 and c516563.

📒 Files selected for processing (1)

• build-apisix-runtime.sh

---

_{Comment @coderabbitai help to get the list of available commands.}

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.