🔒️(agents) upgrade OpenSSL to address CVE-2025-15467

Upgrade OpenSSL and related dependencies to address CVE-2025-15467
in meet-agents.

This vulnerability was blocking the image signature workflow, as it
is classified as a critical dependency.

src/agents/Dockerfile

@@ -4,6 +4,8 @@ FROM python:3.13-slim AS base
 RUN apt-get update && apt-get install -y \
     libglib2.0-0 \
     libgobject-2.0-0 \
+    "openssl=3.5.4-1~deb13u2" \
+    "libssl3t64=3.5.4-1~deb13u2" \
     && rm -rf /var/lib/apt/lists/*
 
 FROM base AS builder