[ADD] php 7.4 strong typing and update dependencies

Update dependencies and add phpdoc for static methods

Preparing v4.1

Merge pull request #50 from mbadolato/master

Tweak to allow the latest release of ramsey/uuid

Merge pull request #37 from nicolopignatelli/rename_string_to_string_…

…literal

Rename String to StringLiteral, Null to NullValue. Publish v3.x.

Prepare next minor release

Updated library description

Dump master version

Dump dev-master version