Fix "Is not a valid Timezone"

Bumping version for `isValidTimezone` fixes #256

Lavachart is using listAbbreviations method to check timezone, the recomendation is to use listIdentifiers method instead.

Related Issue:
[Lavachart america/sao_paulo is not a valid timezone #256](https://github.com/kevinkhill/lavacharts/issues/256#)

should solve #235

manually requiring HasOptionsTrait since it is needed before the Psr4 Autoloader can run. Moving the options initialization to post loader registration. Fixes #227

moving contributors from composer to separate file

Updating config publishing line and version

Fix isValidTimeZone under MacOS X

updating version to 3.1.5