WordPress Real Media Library 4.22.15

build: plugin tested for WordPress 5.7 (CU-f4ydk2)
docs: improve wordpress.org product description (CU-fk36dn)

fix
: renaming a folder did work, but no success message (CU-fb02e3)

fix
newly folders are not draggable and droppable without page reload
newly uploaded media attachments were missing when filtering media items by date due to lack of cache invalidation
respect language of newsletter subscriber to assign to correct newsletter (CU-aar8y9)