Upgrade phpunit

Remove assertions testing errors and notices

Avoid PHPUnit deprecation

Merge pull request #20 from jfredon/fix_map_test_for_Set

Fix test for Set::map()

Merge pull request #18 from simPod/xdebug3

Introduce Xdebug 3 support

Remove object cast sum tests

Merge pull request #9 from NoodlesNZ/master

Add assertions and expected exceptions to risky tests

Update capacity tests and bool cast test

Update data providers and capacity test adjustments

Add null coalesce and reference tests