Add PR template, issue templates, and run metadata check on every PR

[salemaljebaly]

Hi! First, thank you for maintaining this repo and taking the time to review contributions — it's a great resource for the community.

I've been contributing a few tutorials recently and noticed a few small gaps in the contributor workflow that could reduce friction for both contributors and reviewers:

1. PR template
Contributors currently have to manually copy-paste the certification statement from contributing.md into every PR. A .github/PULL_REQUEST_TEMPLATE.md with the statement pre-filled (plus a short checklist) would make this automatic.

2. Issue templates
There's currently no structure for issues — bug reports, update requests, and tutorial ideas all arrive as free-form text. A few issue templates (broken/outdated tutorial, update request, new tutorial idea) would help triage.

3. Trigger metadata validation on every PR push
The check-metadata-in-files workflow currently only runs when the ready label is applied. This means contributors don't get feedback until a reviewer manually triggers it — which can take hours or days. Running validation on every push to a PR would surface errors earlier and reduce the reviewer's workload.

Happy to open a PR for any or all of these if they sound useful.

[salemaljebaly]

@svenja11 would to hear your thoughts on these suggestions.

[svenja11]

Hello @salemaljebaly, sorry for the delay in the response. The metadata validation currently doesn't always work as expected and I didn't have time yet to fix it. So running it only when the ready label is set, is probably best until the issue is fixed. Your other suggestions are good ideas 🙂