ci: pass --security-opt seccomp=unconfined to 386 test container

Ubuntu 26.04 runners currently ship Docker 29.4.2, whose default seccomp profile blocks socketcall(2) with ENOSYS (actions/runner-images#14790). Since Go on linux/386 still uses socketcall(2) for socket operations (golang/go#79200), all tests opening sockets fail with 'socket: function not implemented' when ubuntu-latest lands on ubuntu-26.04.

Signed-off-by: Bartek Plotka <bwplotka@google.com>

.github/workflows/ci.yml

@@ -54,6 +54,10 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: quay.io/prometheus/golang-builder:1.27-base
+      # Docker 29.4.2 on ubuntu-26.04 blocks socketcall(2) in its default seccomp profile
+      # (https://github.com/actions/runner-images/issues/14790), which Go on linux/386
+      # still uses for socket operations (https://github.com/golang/go/issues/79200).
+      options: --security-opt seccomp=unconfined
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with: