Make composer aware of the requirement for 64bits PHP

[stof]

this way, when running on a 32bits version of PHP, Composer will know it cannot use those releases (too bad this was not done in the 2.0.0 release)

[paragonie-security]

Not sure why appveyor is trying to run in the master branch.

Thanks, we were unaware of php-64bit. That will come in handy!

[paragonie-security]

We're going to pull the 2.0,0 release from Packagist so nobody accidentally installs v2 on a 32-bit OS.

[stof]

Note that the version for this php-64bit package is the same than for the php package (but only if your PHP is a 64 bits build). So there is 3 ways to use this requirement:

1. keep the php requirement and use * as the php-64bit constraint (same than the recommended * constraint for ext-* packages for core PHP extensions)
2. duplicate the php requirement in the php-64bit constraint
3. keep only the php-64bit requirement (with the appropriate constraint)

I prefer option 1 (which is what I implemented here):

• option 2 duplicates the requirement, making it easy to create a weird state when updating the PHP requirement (the actual PHP requirement ending up being a AND between both constraints)
• option 3 is equivalent to option 1 as far as composer 2.5+ is concerned. However, other tooling (including the version guessing in composer require for Composer 2.4 and older) might rely on a php requirement without checking whether a php-64bit restricts the PHP version range as well (especially because requirements on php-64bit are not common and often unknown). So option 1 is safer than option 3 regarding support in various tools.

[stof]

Maybe https://paragonie.com/blog/2024/04/release-sodium-compat-v2-and-future-our-polyfill-libraries should be updated to mention that composer also performs the check for the 64 bits requirement now.

[stof]

@paragonie-security as you removed the 2.0.0 release, you should probably update the release notes of 2.0.1 to include all the informations from 2.0.0. Otherwise, there is no info anymore about the 2.0 changes