@backstage/plugin-techdocs-node vulnerable to arbitrary code execution via MkDocs hooks

Impact When TechDocs is configured with runIn: local, a malicious actor who can submit or modify a repository's mkdocs.yml file can execute arbitrary Python code on the TechDocs build server via MkDocs hooks configuration. Patches Upgrade to @backstage/plugin-techdocs-node version 1.13.11, 1.14.1...