fix(ci): ignore backstage app, app-next (if exist) and backend packages when release plugins

[jerolimov]

Hey, I just made a Pull Request!

This fixes #1508 by simple ignoring the "app", "app-next" (if exist) and "backend" when running yarn changeset version.

I tried this locally in the npm package, that contains a changeset and a backstage app.

Without this ignore list it touches this files:

	deleted:    .changeset/proud-brooms-clean.md
	modified:   packages/app/package.json
	modified:   plugins/npm/package.json
	new:        packages/app/CHANGELOG.md
	new:        plugins/npm/CHANGELOG.md

With this change it touches only:

	deleted:    .changeset/proud-brooms-clean.md
	modified:   plugins/npm/package.json
	new:        plugins/npm/CHANGELOG.md

I added this for all projects with packages.

code workspaces/*/packages/../.changeset/config.json

Fyi: I tried first yarn changeset version --ignore app --ignore backend, which works fine on projects with an backstage app, but is fails on these workspaces without.

✔️ Checklist

• A changeset describing the change and affected packages. (more info)
• Added or updated documentation
• Tests for new functionality and regression tests for bug fixes
• Screenshots attached (for UI changes)
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