Fix phpunit deprecations (phpbench#619)

* Removed expect exception message annotations

* Migrate expectedException annotations

* Fix deprecated PHPUnit methods

* Enable fail on warnings in phpunit

* CS fixes

* Open file for read/write (fix issue with PHP 7.4)

We echo the written output to STDOUT - but previously we
did not open it for reading, whereas in PHP < 7.4 it didn't
seem to matter ...

* Do not allow failures with 7.4

* Handle edge case where min is 0 (avoid div by zero)

Updated CHANGELOG

set version

use php to execute box

use humbug/box for GH releases and @git_tag@ for version

only deploy the PHAR

deploy pubkey with correct extension

deploy asc file

also upload the signature on deploy

deploy to github releases