Support for phive, sign PHAR builds

[tvbeek]

Description

I think that if we have signed PHAR files for PHPMD we can use the same for PHP_Depend. The steps that are needed:

• Finish #521 Sign PHAR builds phpmd/phpmd#688
• Create and publish a key (I suspect @ravage84 need to do this)
• Create a PR to sign the PHAR files.
• Create a PR for https://github.com/phar-io/phar.io/blob/master/data/repositories.xml to add this project to the list.

Checks before submitting

• Be sure that there isn't already an issue about this. See: Issues list
• Be sure that there isn't already a pull request about this. See: Pull requests
• Tell if you have the option to provide the code for this proposal.
• This issue is about 1 feature proposal and nothing more.
• The issue has a descriptive title. For example: "Support nullable types".

[tvbeek]

And then I see we miss the phar file in the releases (See #364 ) There is a pull request #372 but that does multiple things.

[tvbeek]

@ravage84 I assign this to you because if I'm correctly the only missing step is the keys that you need to set in the secrets 😃

Sorry wrong project.

[tvbeek]

This is already finished