v8.6: julia_publish: install aws-kms-pkcs11 for KMS-backed docs deploy (#289)

The julia-publish pipeline's publish_all step gains a docs-deploy phase that
pushes the built HTML docs to docs.julialang.org over SSH, signing with a
deploy key whose private half lives only in AWS KMS. SSH reaches the key
through the aws-kms-pkcs11 PKCS#11 provider, which this image previously
lacked. Install the upstream prebuilt, statically-linked module (v0.0.17,
ubuntu24.04 build -- matches Debian trixie's OpenSSL 3) at the standard
p11-kit module path, pin its sha256, and verify all NEEDED libraries resolve
(its only out-of-image runtime dependency is libjson-c5).

Co-authored-by: Keno Fischer <Keno@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>