Release v3.0.0

Added

• Switch to PSR18 client implementation and bump httplug minimum version to ^2.0 (GrahamCampbell) #885
• Switch to PSR-17 and remove deprecated code (GrahamCampbell) #888
• Allow PHP8 (acrobat) #934
• [3.x] Make PHP 7.2.5 the minimum version (GrahamCampbell) #942
• [3.x] Re-worked pagination to not mutate the api classes (GrahamCampbell) #907 & (acrobat) #956
• Prepare 3.0 release and remove remaining deprecated code (acrobat) #948

Changed

• Remove BC check on 3.x (GrahamCampbell) #900
• [3.x] Fix the HTTP methods client (GrahamCampbell) #910
• fix typo (michielkempen) #920
• [3.x] Added some additional scalar types and return types (GrahamCampbell) #949