Run poetry-check on push to main, so main stops showing 6/8

[adamjohnwright]

main has been showing 6/8 checks on every commit. The cause is not a failure — it is a skip.

poetry-check carried:

if: ${{ github.event_name == 'pull_request' || github.event_name == 'workflow_dispatch' }}

so a push to main skipped it, on both matrix legs. GitHub counts a skipped required check as not-passing, and poetry-check (ubuntu-latest) is one of the four required contexts. Hence 6/8, permanently.

Why not just delete the if:

Because the job would then be expensive on every push. The lockfile diff reads github.base_ref, which is empty outside a pull request, and the empty case fell through to "manual run: no base to compare against, so always verify" — the full Python + Poetry install and import verification, on both ubuntu-latest and macos-15-intel, for every commit to main.

A push does have something to compare against: the commit before it. So the empty-base case now splits — push diffs HEAD^..HEAD, workflow_dispatch keeps verifying unconditionally as it has nothing to compare against.

Verification

The shell block was extracted and run against real commits in this repository, with the GitHub expressions substituted:

event	base_ref	commit	result
push	—	one that changed poetry.lock	changed=true
push	—	one that did not	changed=false
workflow_dispatch	—	HEAD	changed=true
pull_request	main	HEAD	changed=false

fetch-depth: 0 is already set, so HEAD^ resolves.