Check: Don't allow to use minor versions in Tested Up

[davidperezgar]

In our reviews we do not allow to use minor versions in Tested Up header. We ask the autor to change te version like this:

ERROR: Tested up to: "6.7.1" needs to be just the major version number. Example: Tested up: 6.7
ℹ️ Please, include only the major WordPress version, as the minor version is ignored.

So we will have to make the check to accomplish this guideline.