Unpin or update GN version

[targos]

Node.js 14 is EoL.

build/ansible/roles/gn/vars/main.yml

Lines 9 to 12 in 612dcfe

	gn_select_compiler: "{{ compiler[os]|default(compiler[os|stripversion])|default('true') }}"
	# Pin gn for now so we can still build older versions of V8 in Node.js 14.
	# Refs: https://github.com/nodejs/node/pull/40689#issuecomment-956303875
	gn_version: 69ec4fc

[github-actions]

This issue is stale because it has been open many days with no activity. It will be closed soon unless the stale label is removed or a comment is made.

[richardlau]

Rolling forward the gn version in #3659.
For now I've just rolled the version to a later commit (within the last few weeks). While we could unpin that might risk the machines having differing versions of gn on them which might make diagnosing any future issues tricky.