feature(versioning): change version strategy for php7-scalar_objects

[xarem]

we should change the version strategy for php7-scalar_objects because they don't have a versioning strategy in their repository and are using the master branch.

Instead of using an own version number we could use the git ref and a pkgver like YYYYMMDD like in secp256k1.

[xarem]

what's your opinion, @hernandev?

[hernandev]

date versioning works form e @xarem lets change that, if we did not yet

[hernandev]

@xarem just like imagick is being built right now, from git, there is a way for doing that, the version may be that but lets stop using the master zip as well and fix a git rev