chore: add githubnext.github.io to pelis-agent-factory-advisor domain allowlist

[Copilot]

The pelis-agent-factory-advisor workflow uses web-fetch to crawl documentation at https://githubnext.github.io/gh-aw/blog/, but this domain was missing from the network allowlist.

Changes

• Added githubnext.github.io to network.allowed in the workflow frontmatter

network:
  allowed:
    - github
    - "githubnext.github.io"

Original prompt

add githubnext.github.io to domain allowlist to pelis agent factory advisor agent

Custom agent used: upgrade-agentic-workflows
Upgrade agentic workflows to the latest version of gh-aw with automated compilation and error fixing

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