fix: Security Scan fails on Go 1.26.8, golang.org/x/net v0.58.0 and amqp091-go v1.13.0 CVEs #81

Problem

The Security Scan job (make trivy-gate) fails on every branch, It has been red on main since 2026-09-15. Trivy 0.74 reports 13 findings (4 in trivy-deps.sarif, 9 in trivy-image.sarif):

Failing run: https://github.com/OpenAgriNet/network-adapter/actions/runs/38214427678/job/114695729451

Fix

• go.mod: go 1.26.8 → go 1.26.9. CI reads the version from go-version-file: go.mod, so the workflows pick it up without changes.
• go get golang.org/x/net@v0.60.0 github.com/rabbitmq/amqp091-go@v1.14.0, then go mod tidy. x/net v0.60.0 also requires newer golang.org/x/crypto (v0.57.0), x/sys (v0.48.0), x/text (v0.42.0) and x/sync (v0.23.0).
• Dockerfile.adapter and Dockerfile.adapter-with-plugins: golang:1.26.8-bookworm → golang:1.26.9-bookworm. The image binary is built with this toolchain, so the image scan stays red without it.
• README: change the "Go 1.26.8 or higher" note to 1.26.9.

Stay on the 1.26 line. 1.27.2 also fixes these CVEs, but moving to a new minor Go release is a separate decision.

Acceptance criteria

• make build and make test pass on Go 1.26.9
• make trivy-deps, make trivy-image and make trivy-gate report 0 findings
• Security Scan is green on the PR
• No application code changes