php 8.0 needed for 'mixed' type

Merge pull request #27 from outlandishideas/2023-11-30-make-return-ty…

…pes-compatible-with-parent

Make return types of functions compatible with parents

Merge pull request #24 from szepeviktor/patch-1

Fix title retrieval

Merge pull request #25 from outlandishideas/composer-installers-2

Support composer installers 2

Adding new fetchIds function and corresponding handling in get_posts;

Caching postTypeParent result to save repeated lookups

Merge pull request #20 from outlandishideas/19-exc-attachments

Exclude attachments from `OowpQuery`

self -> static

self -> static

Merge pull request #14 from outlandishideas/13-consistent-post-type-c…

…onstraints

Align `fetchOne()` post type constraints with similar methods

Making packagist-compliant