The version constraint checks will also be used in the future to
evaluate whether any given site's PHP constraint (if set) is
valid for the currently linked version of PHP.
For example, assuming you have PHP 8.1.2 linked, we could evaluate:
* A site requires "8.0" -> invalid
* A site requires "^8.0" -> valid
* A site requires "^8.0.0" -> valid
* A site requires "~8.0" -> valid
* A site requires "~8.0.0" -> invalid
Currently, this constraint check is used to determine which versions
that are currently installed are good suggestions to switch to.
If you have a site with constraint "^8.0" for example, and you have
PHP 8.0 and 8.1 installed (with 8.1 linked), then you will get a
suggestion to switch back to 8.0.
